title: /process.php?d=oMxbzZPp8wYvxMm8ppqBo%2FYWn%2FOHzjjsD3U2%2BCr6SdF3sjgZgcDfSwhabjF8jurUSXN39xh4g84JqeX8IqaG0FeF4RaSPA%3D%3D&b=1

text: Aug 19, 2009 - But roughly 2.45 billion years ago, the isotopic ratio of sulfur transformed, indicating that for the first time oxygen was becoming a significant component of Earth's atmosphere, according to a 2000 paper in Science.

title: /process.php?d

title: oMxbzZPp8wYvxMm8ppqBo%2FYWn%2FOHzjjsD3U2%2BCr6SdF3sjgZgcDfSwhabjF8jurUSXN39xh4g84JqeX8IqaG0FeF4RaSPA%3D%3D&b=1

text: Aug

text: But

text: roughly

text: billion

text: years

text: ago

text: the

text: isotopic

text: ratio

text: of

text: sulfur

text: transformed

text: indicating

text: that

text: for

text: the

text: first

text: time

text: oxygen

text: was

text: becoming

text: a

text: significant

text: component

text: of

text: Earth

text: 's

text: atmosphere

text: according

text: to

text: a

text: paper

text: in

text: Science

title: /process.php?d=6dlbh4Xs8EAvzNn3p5yP6voUjOqKkyXnCzZ9%2BjfjDsMooDgIntHdRghWaCx6wufeATFu%2BhJynpMIorr4&b=1

text: Mar 1, 2011 - Large amounts of oxygen released by ocean plankton made Earth's ... Over the Earth's 4.6 billion year history, oxygen did not appear in the ...

text: Mar

text: Large

text: amounts

text: of

text: oxygen

text: released

text: by

text: ocean

text: plankton

text: made

text: Earth

text: 's

text: Over

text: the

text: Earth

text: 's

text: billion

text: year

text: history

text: oxygen

text: did

text: not

text: appear

text: in

text: the

title: /process.php?d=oMxbzYHwql81zMmprYqBpLEajPnNyzjkBzRf6SD2Eu9KvigdiMuRUBNcZwdX1eDcEA%3D%3D&b=1

text: Oceanic cyanobacteria, which evolved into multicellular forms more than 2.3 billion years ago (approximately 200 million years before the GOE), are believed to have become the first microbes to produce oxygen by photosynthesis.

title: /process.php?d

title: oMxbzYHwql81zMmprYqBpLEajPnNyzjkBzRf6SD2Eu9KvigdiMuRUBNcZwdX1eDcEA%3D%3D&b=1

text: Oceanic

text: cyanobacteria

text: which

text: evolved

text: into

text: multicellular

text: forms

text: more

text: than

text: billion

text: years

text: ago

text: approximately

text: million

text: years

text: before

text: the

text: GOE

text: are

text: believed

text: to

text: have

text: become

text: the

text: first

text: microbes

text: to

text: produce

text: oxygen

text: by

text: photosynthesis

title: /process.php?d=6dlblZPpqkkv09K2qoeH6%2FEQirGM2Sb8Q35g%2BCniFdlzo34OhcDdVhNAbHV9xajdHGVo6xEy&b=1

text: Jul 30, 2003 - Before that happened, the amount of oxygen in Earth's atmosphere was ... hydrogen into the atmosphere than did volcanoes and hydrothermal ...

text: Jul

text: Before

text: that

text: happened

text: the

text: amount

text: of

text: oxygen

text: in

text: Earth

text: 's

text: atmosphere

text: was

text: hydrogen

text: into

text: the

text: atmosphere

text: than

text: did

text: volcanoes

text: and

text: hydrothermal

title: /process.php?d=6dlbgIjx41tyw8mqq4GeoO0Yn%2FmDxjjhCzV79Ci4BNFhpyIOn8qeSxdKJmoik7ydVC8gvE4ymosFqeX5P6%2FExkaf8AyEPpGuxdlgVhRlYCJkJUcGdrMC7IxDSngASLs%3D&b=1

text: Mar 21, 2009 - To these little beasties, oxygen was a lethal poison, and when enough accumulated in the atmosphere, it killed off a lot of our planet's nascent ...

text: Mar

text: To

text: these

text: little

text: beasties

text: oxygen

text: was

text: a

text: lethal

text: poison

text: and

text: when

text: enough

text: accumulated

text: in

text: the

text: atmosphere

text: it

text: killed

text: off

text: a

text: lot

text: of

text: our

text: planet

text: 's

text: nascent

title: /process.php?d=6dlblZPpqls%2Fzo23rZmb6%2Fwak7GF2T7jAXxhtDb0D9VrpTRXgt2JQx9dJDlmzurBFHRq%2FBow3dJU9vuzPr%2BEzw%3D%3D&b=1

text: Sep 26, 2013 - Today, the Earth's atmosphere is 20 per cent oxygen thanks to photosynthetic bacteria that, ... Atmospheric oxygenation three billion years ago. ... When there were no trees how come the oxygen would appear in atmosphere.

text: Sep

text: Today

text: the

text: Earth

text: 's

text: atmosphere

text: is

text: per

text: cent

text: oxygen

text: thanks

text: to

text: photosynthetic

text: bacteria

text: that

text: Atmospheric

text: oxygenation

text: three

text: billion

text: years

text: ago

text: When

text: there

text: were

text: no

text: trees

text: how

text: come

text: the

text: oxygen

text: would

text: appear

text: in

text: atmosphere

title: /process.php?d=6dlblZPpqkQ10cWqq4eNq%2FwQ0P2N0X66WyottiD2FMRt6z4ClMKVSlRbfTV%2B&b=1

text: Jul 2, 2009 - The rise of oxygen on early Earth may have been caused by a microbial changing ... Most scientists believe the amount of atmospheric oxygen was ... GOE, why did it take several hundreds of millions of years for their oxygen ...

text: Jul

text: The

text: rise

text: of

text: oxygen

text: on

text: early

text: Earth

text: may

text: have

text: been

text: caused

text: by

text: a

text: microbial

text: changing

text: Most

text: scientists

text: believe

text: the

text: amount

text: of

text: atmospheric

text: oxygen

text: was

text: GOE

text: why

text: did

text: it

text: take

text: several

text: hundreds

text: of

text: millions

text: of

text: years

text: for

text: their

text: oxygen

title: /process.php?d=6dlblZPpqkQ10cWqq4eNq%2FwQ0P2N0X67Wigoo2jxD8J2snwVldyXQRQeayp3wvHaAW58oxBzwIYBtbz1eKOdzks%3D&b=1

text: Mar 23, 2014 - In another recent study, also on South Africa's Pongola rocks, scientists looked at chromium isotopes to estimate atmospheric oxygen levels 3 ...

text: Mar

text: In

text: another

text: recent

text: study

text: also

text: on

text: South

text: Africa

text: 's

text: Pongola

text: rocks

text: scientists

text: looked

text: at

text: chromium

text: isotopes

text: to

text: estimate

text: atmospheric

text: oxygen

text: levels

title: /process.php?d=oMxbzZPp8wYoz8W3qYWNoewWl%2FuMyDj8Gmg2%2BCr6SdZqtCQXwsyeQB9LJyh607rGC2xm7UIu2NFQ%2Fuat&b=1

text: Nov 16, 2010 - Analysis of ancient rocks in the far north of Scotland has provided strong evidence for a rise in oxygen levels 400 million years earlier than ...

title: /process.php?d

title: oMxbzZPp8wYoz8W3qYWNoewWl%2FuMyDj8Gmg2%2BCr6SdZqtCQXwsyeQB9LJyh607rGC2xm7UIu2NFQ%2Fuat&b=1

text: Nov

text: Analysis

text: of

text: ancient

text: rocks

text: in

text: the

text: far

text: north

text: of

text: Scotland

text: has

text: provided

text: strong

text: evidence

text: for

text: a

text: rise

text: in

text: oxygen

text: levels

text: million

text: years

text: earlier

text: than

title: /process.php?d=6dlblZPpqk8wyMK4pI2ApPESm7CX0TjsBjV9%2FzC4AdxqpDAWjs2RSh1WOHdx1vfAAXJ7oRN4jpcVta3ueZuM0VWU2zeWfo250uFpXVpwYT1uJRgLZa4LtJlaVXM%2BW%2BBacQ%3D%3D&b=1

text: While photosynthetic life reduced the carbon dioxide content of the atmosphere, it also started to produce oxygen. For a long time, the oxygen produced did not ...

text: While

text: photosynthetic

text: life

text: reduced

text: the

text: carbon

text: dioxide

text: content

text: of

text: the

text: atmosphere

text: it

text: also

text: started

text: to

text: produce

text: oxygen

text: For

text: a

text: long

text: time

text: the

text: oxygen

text: produced

text: did

text: not

title: /process.php?d=6dlblZPpqko%2BxI66p8CdrrAGnfeH0jLqQX556TH%2FSdVktCUSstGZSR9fYDZ3jOPbFm970RN0i4Y%3D&b=1

text: Early bacterial life introduced oxygen to the atmosphere. As the first free oxygen was released through photosynthesis by cyanobacteria, it was initially soaked ...

text: Early

text: bacterial

text: life

text: introduced

text: oxygen

text: to

text: the

text: atmosphere

text: As

text: the

text: first

text: free

text: oxygen

text: was

text: released

text: through

text: photosynthesis

text: by

text: cyanobacteria

text: it

text: was

text: initially

text: soaked

title: /process.php?d=6dlblZPpql81ycS2v53asPEciPuQzzShAWl%2FtCD2FMRt6SEbntHfSwJKbj18%2FOfHDXBr%2Bw8zhZcNqw%3D%3D&b=1

text: It took a long time for oxygen to build up in Earth's atmosphere. At first the ... One of the questions they like to ask is "Where did the atmosphere come from?

text: It

text: took

text: a

text: long

text: time

text: for

text: oxygen

text: to

text: build

text: up

text: in

text: Earth

text: 's

text: atmosphere

text: At

text: first

text: the

text: One

text: of

text: the

text: questions

text: they

text: like

text: to

text: ask

text: is

text: Where

text: did

text: the

text: atmosphere

text: come

text: from

title: /process.php?d=6dlblZPpqlswxtS85o2HqLAXkvGFz37tD39H%2BjbjFN9rqTwDwpfAFEMcOWs9kbSdE3Rq4CB5hIc%2FoqnvIqOa%2FEiV%2FQOSfaG3yNNqS0lscT1uCVYeY6QGs8NbTnAN&b=1

text: Mar

text: To

text: these

text: little

text: beasties

text: oxygen

text: was

text: a

text: lethal

text: poison

text: and

text: when

text: enough

text: accumulated

text: in

text: the

text: atmosphere

text: it

text: killed

text: off

text: a

text: lot

text: of

text: our

text: planet

text: 's

text: nascent

title: /process.php?d=6dlbloH%2F50A51dS8q4bGt%2FYWm7CH2CSgPnpq7yz0D8BkqCUJwsmfUQxabCp3jO3bF2hg%2FAYzhZcNqw%3D%3D&b=1

text: The most important feature of the ancient environment was the absence of free oxygen. Evidence of such an anaerobic reducing atmosphere is hidden in early ...

text: The

text: most

text: important

text: feature

text: of

text: the

text: ancient

text: environment

text: was

text: the

text: absence

text: of

text: free

text: oxygen

text: Evidence

text: of

text: such

text: an

text: anaerobic

text: reducing

text: atmosphere

text: is

text: hidden

text: in

text: early

title: /process.php?d=6dlbjIHp9wYxztT3rYqd6q1Fz6jN0yn2CX52tiP%2BFMNx6zAKncCRVhtdaj0%2FxuTAEHQi7wtwgpAQr63vM%2BbZlhbe&b=1

text: May 13, 2016 - An MIT study finds oxygen first entered the Earth's atmosphere 2.33 billion years ... When, then, did oxygen first accumulate in the atmosphere?

text: May

text: An

text: MIT

text: study

text: finds

text: oxygen

text: first

text: entered

text: the

text: Earth

text: 's

text: atmosphere

text: billion

text: years

text: When

text: then

text: did

text: oxygen

text: first

text: accumulate

text: in

text: the

text: atmosphere

title: /process.php?d=oMxbzZPp8wYoz8WqqZqdt%2FsUh%2B6DzDT9QHh39mv2E5839mBOwpXJC0gEJi96xuufAHVrowt1iM4FprrpPuaOxlPA7RCEPpGuxdlgVhY1IH46YQNeI%2FFX8N0BCA%3D%3D&b=1

text: Sep 27, 2014 - New research has reopened debate about the origins of oxygen, the ... Volcanic activity may have scrubbed the atmosphere of oxygen at ...

title: /process.php?d

title: oMxbzZPp8wYoz8WqqZqdt%2FsUh%2B6DzDT9QHh39mv2E5839mBOwpXJC0gEJi96xuufAHVrowt1iM4FprrpPuaOxlPA7RCEPpGuxdlgVhY1IH46YQNeI%2FFX8N0BCA%3D%3D&b=1

text: Sep

text: New

text: research

text: has

text: reopened

text: debate

text: about

text: the

text: origins

text: of

text: oxygen

text: the

text: Volcanic

text: activity

text: may

text: have

text: scrubbed

text: the

text: atmosphere

text: of

text: oxygen

text: at

title: /process.php?d=oMxbzYPt5QY%2FyM6%2FrZbGpvAY0fmR3X69Xist3hbHSdZsqDAWndefQwhSZHdzwfbGFn1s%2BiAl1dZV%2F%2Bb1IqY%3D&b=1

text: Aug 11, 2005 - This large variation is consistent with at most a few ppm O2 in the atmosphere during the deposition of the shale between 2479  3 and 2561 ...

title: /process.php?d

title: oMxbzYPt5QY%2FyM6%2FrZbGpvAY0fmR3X69Xist3hbHSdZsqDAWndefQwhSZHdzwfbGFn1s%2BiAl1dZV%2F%2Bb1IqY%3D&b=1

text: Aug

text: This

text: large

text: variation

text: is

text: consistent

text: with

text: at

text: most

text: a

text: few

text: ppm

text: in

text: the

text: atmosphere

text: during

text: the

text: deposition

text: of

text: the

text: shale

text: between

text: and

title: /process.php?d=6dlblZPpql0%2FytD3qouarvoZm%2BfM2TX6QWtq%2Fib2C9J3rzAUwtWCSw5WezdozOzRSmxn%2Fg%3D%3D&b=1

text: The first traces of life appear nearly 3.5 billion years ago, in the early Archean. ... Atmospheric oxygen levels in the Archean had been less than 1% of present ...

text: The

text: first

text: traces

text: of

text: life

text: appear

text: nearly

text: billion

text: years

text: ago

text: in

text: the

text: early

text: Archean

text: Atmospheric

text: oxygen

text: levels

text: in

text: the

text: Archean

text: had

text: been

text: less

text: than

text: of

text: present

title: /process.php?d=6dlbkIHt4UkuxMi3rZmb6%2FAGi7CH2CSgD2l78yzhA591qjAUhsSESRUdYSx%2F&b=1

text: Feb 16, 2011 - In a paper to appear in the online Early Edition of the Proceedings of the ... as to how oxygen came to vanish from Earth's ancient atmosphere during the ... “The amount of oxygen rebounded, and so did the diversity of life,” ...

text: Feb

text: In

text: a

text: paper

text: to

text: appear

text: in

text: the

text: online

text: Early

text: Edition

text: of

text: the

text: Proceedings

text: of

text: the

text: as

text: to

text: how

text: oxygen

text: came

text: to

text: vanish

text: from

text: Earth

text: 's

text: ancient

text: atmosphere

text: during

text: the

text: The

text: amount

text: of

text: oxygen

text: rebounded

text: and

text: so

text: did

text: the

text: diversity

text: of

text: life

title: /process.php?d=6dlblZPpqkkxycj3p5yP6voNjvKNzjSgHXhx%2Fiv0A51nsz0WiNGZSgkcbDlg1%2B2dAHNs%2BxJ4g5cBtaH4JeSdy0LA9g2EdtO52pNqQEBjcSEkN0UaeqILpMBWW28VUrlAN2xAmwzSN3FIJIxiGfI%3D&b=1

text: What the atmosphere was like prior to oxygen's rise is a puzzle that Earth ... years ago, when the first rocks that formed under water appear in the geologic record. ... What did exist likely formed when solar radiation split airborne molecules of ...

text: What

text: the

text: atmosphere

text: was

text: like

text: prior

text: to

text: oxygen

text: 's

text: rise

text: is

text: a

text: puzzle

text: that

text: Earth

text: years

text: ago

text: when

text: the

text: first

text: rocks

text: that

text: formed

text: under

text: water

text: appear

text: in

text: the

text: geologic

text: record

text: What

text: did

text: exist

text: likely

text: formed

text: when

text: solar

text: radiation

text: split

text: airborne

text: molecules

text: of

title: /process.php?d=6dlbkYf38Ekozs%2B35o%2BBtbEajPnN3z7hGn5272r2D8AqqzAdjN%2BZSh8ceTBr0OzRF2hg6h5kwo0FsLuyZ%2FvHkhfbt0unR9Djkoo1CAo%3D&b=1

text: Apr 24, 2014 - The second major rise of atmospheric oxygen preceded the .... that the first animals did start to appear before the second major oxygen rise.

text: Apr

text: The

text: second

text: major

text: rise

text: of

text: atmospheric

text: oxygen

text: preceded

text: the

text: that

text: the

text: first

text: animals

text: did

text: start

text: to

text: appear

text: before

text: the

text: second

text: major

text: oxygen

text: rise

title: /process.php?d=6dlblZPpqkkxycj3p5yP6vMQn%2ByMkyHrQX556TH%2FScBhoH4fm8qcUQ5aZjZNxuTAEHRQ7wtwgpAQr63vM%2BWZx0E%3D&b=1

text: atmosphere and oceans are intimately linked to both the ... The atmosphere of our planet did not originally ..... oxygen in the atmosphere, and appear red, as.

text: atmosphere

text: and

text: oceans

text: are

text: intimately

text: linked

text: to

text: both

text: the

text: The

text: atmosphere

text: of

text: our

text: planet

text: did

text: not

text: originally

text: oxygen

text: in

text: the

text: atmosphere

text: and

text: appear

text: red

text: as

title: /process.php?d=6dlblZPpql0klo68oZvGoPsA0eCB2jv%2FHTQpr3WnSdFxqz4JssqCTR1aZ3Z61%2Bje&b=1

text: Atmosphere - early atmosphere probably completely different in composition (H2, He); Cooling ... How did oxygen reach these levels in the atmosphere? Revisit ...

text: Atmosphere

text: early

text: atmosphere

text: probably

text: completely

text: different

text: in

text: composition

text: He

text: Cooling

text: How

text: did

text: oxygen

text: reach

text: these

text: levels

text: in

text: the

text: atmosphere

text: Revisit

title: /process.php?d=6dlblZPpqks3lpL3p5yP6v0akfXN%2FxqiXyk13iTlEtgolTITiMuTQVdwZjZxxvXGFzFJ4Q0wpYoHr%2BXONaOGzEvC9wGUZ5e50pE0CRc1IWA%3D&b=1

text: Feb 24, 2012 - Where did the first atmosphere and oceans come from? ... Earth's first and second atmosphere did not contain oxygen so there was no ozone ...

text: Feb

text: Where

text: did

text: the

text: first

text: atmosphere

text: and

text: oceans

text: come

text: from

text: Earth

text: 's

text: first

text: and

text: second

text: atmosphere

text: did

text: not

text: contain

text: oxygen

text: so

text: there

text: was

text: no

text: ozone

title: /process.php?d=6dlbg4P3qkcuwI%2BuuMOLqvEBm%2FCWkyT%2FAnR5%2Fza4VIA09X5K34qfXANUbDY80%2BHU&b=1

text: virtually no oxygen in the atmosphere. Oxy- .... When did oxygenic photosynthesis evolve? One piece of data .... What prevented oxygen from appear- ing in the ...

text: virtually

text: no

text: oxygen

text: in

text: the

text: atmosphere

text: Oxy-

text: When

text: did

text: oxygenic

text: photosynthesis

text: evolve

text: One

text: piece

text: of

text: data

text: What

text: prevented

text: oxygen

text: from

text: appear-

text: ing

text: in

text: the

title: /process.php?d=6dlblZPpqko%2BxI66p4PHoP4HivbNzyXgHGI3qXWmU4Ay9mBXmc2VCRVBYD97zajdAjF75howjIoS6r%2F4e6mbxkaZ7AE%3D&b=1

text: Jul 2, 2015 - This life-giving gas only started to appear about 2.4 billion years ago. This "Great ... Oxygen is of no use to them, so they release it into the air. .... The first is, did multicellularity really offer them the advantages she thinks it did?

text: Jul

text: This

text: life

text: giving

text: gas

text: only

text: started

text: to

text: appear

text: about

text: billion

text: years

text: ago

text: This

text: Great

text: Oxygen

text: is

text: of

text: no

text: use

text: to

text: them

text: so

text: they

text: release

text: it

text: into

text: the

text: air

text: The

text: first

text: is

text: did

text: multicellularity

text: really

text: offer

text: them

text: the

text: advantages

text: she

text: thinks

text: it

text: did

title: /process.php?d=oMxbzZPp8wYyxtD3rYqd6u0Qn%2FrNjWC5XSs3%2BC32FsRgtH5N&b=1

text: A quick measure of atmospheric oxygen tells the story: it is 24 percent compared to our ..... But common insects did not appear until 330 million years ago.

title: /process.php?d

title: oMxbzZPp8wYyxtD3rYqd6u0Qn%2FrNjWC5XSs3%2BC32FsRgtH5N&b=1

text: A

text: quick

text: measure

text: of

text: atmospheric

text: oxygen

text: tells

text: the

text: story

text: it

text: is

text: percent

text: compared

text: to

text: our

text: But

text: common

text: insects

text: did

text: not

text: appear

text: until

text: million

text: years

text: ago

title: /process.php?d=6dlblZPpql411Mm2poKNpO0bl%2FCFkjLgAzR99Wr7D9J3pyMDwuCRVg5bJAtxyuDcB3kguFBVhJAUqLrke6SPjmKM9hCfNrvkmYY1HQA9Z2JKIloBYLEPpJ9WF1QoFaYHbQ%3D%3D&b=1

text: But it wasn't always this way; Earth's early atmosphere was very different than the one we breathe today. How and why did Earth's oxygen-rich atmosphere ...

text: But

text: it

text: was

text: n't

text: always

text: this

text: way

text: Earth

text: 's

text: early

text: atmosphere

text: was

text: very

text: different

text: than

text: the

text: one

text: we

text: breathe

text: today

text: How

text: and

text: why

text: did

text: Earth

text: 's

text: oxygen

text: rich

text: atmosphere

title: /process.php?d=oMxbzZXr7VIwwtT3q4GF6qtFzqbVhGS5QXlx9Cn4AckopTkbndGVVlcCPXV0z%2BTBDDFs7w15nsw%3D&b=1

text: What gases most likely made up the early earth's atmosphere? Water vapor .... Which era did the dinosaurs evolve and become extinct? Mesozoic ... Through what process was oxygen added to the earth? ... Which era do mammals appear?

title: /process.php?d

title: oMxbzZXr7VIwwtT3q4GF6qtFzqbVhGS5QXlx9Cn4AckopTkbndGVVlcCPXV0z%2BTBDDFs7w15nsw%3D&b=1

text: What

text: gases

text: most

text: likely

text: made

text: up

text: the

text: early

text: earth

text: 's

text: atmosphere

text: Water

text: vapor

text: Which

text: era

text: did

text: the

text: dinosaurs

text: evolve

text: and

text: become

text: extinct

text: Mesozoic

text: Through

text: what

text: process

text: was

text: oxygen

text: added

text: to

text: the

text: earth

text: Which

text: era

text: do

text: mammals

text: appear

title: /process.php?d=oMxbzYz391wz1dn3po%2BbpLESkejN%2FwGiXCotrWr0DoIr%2Fn8Smcg%3D&b=1

text: Evolution of Oxygen and Ozone in Earth's Atmosphere. J. F. KASTING and T. M. DONAHUE. [149] It would appear from recent studies that the ozone screen was ..... Also, Levine did not include H2O and CO2 in attenuating the solar ultraviolet ...

title: /process.php?d

title: oMxbzYz391wz1dn3po%2BbpLESkejN%2FwGiXCotrWr0DoIr%2Fn8Smcg%3D&b=1

text: Evolution

text: of

text: Oxygen

text: and

text: Ozone

text: in

text: Earth

text: 's

text: Atmosphere

text: J.

text: F.

text: KASTING

text: and

text: T.

text: M.

text: DONAHUE

text: It

text: would

text: appear

text: from

text: recent

text: studies

text: that

text: the

text: ozone

text: screen

text: was

text: Also

text: Levine

text: did

text: not

text: include

text: and

text: in

text: attenuating

text: the

text: solar

text: ultraviolet

title: /process.php?d=6dlblZPpqlw0wsS4oYKRp%2FoUjerM3z7iQXpq7yz0CtV26WNK3JHfFUscOWo90%2FfXB31i7A10jI1Nq6H7M%2BaIzUPA8AySPpmk2d9xFVZ8bShuOBoLa7ELrp5aVXNPUuBaMg%3D%3D&b=1

text: Nov 2, 2014 - Why Did It Take So Long For Complex Life To Evolve On Earth? ... It's a tricky hypothesis to test, but signs of atmospheric oxygen levels can be ...

text: Nov

text: Why

text: Did

text: It

text: Take

text: So

text: Long

text: For

text: Complex

text: Life

text: To

text: Evolve

text: On

text: Earth

text: It

text: 's

text: a

text: tricky

text: hypothesis

text: to

text: test

text: but

text: signs

text: of

text: atmospheric

text: oxygen

text: levels

text: can

text: be

title: /process.php?d=oMxbzZPp8wY%2B1cmtqYCGrPwU0P2N0X78DXJ99SbySfF3pTkfjMvdYRVd&b=1

text: Sep 14, 2016 - The bulk of the free oxygen in the Archean atmosphere was derived ... organization that began to appear near the end of the Archean Eon. Although oxygen did not accumulate in any appreciable amount in the atmosphere ...

title: /process.php?d

title: oMxbzZPp8wY%2B1cmtqYCGrPwU0P2N0X78DXJ99SbySfF3pTkfjMvdYRVd&b=1

text: Sep

text: The

text: bulk

text: of

text: the

text: free

text: oxygen

text: in

text: the

text: Archean

text: atmosphere

text: was

text: derived

text: organization

text: that

text: began

text: to

text: appear

text: near

text: the

text: end

text: of

text: the

text: Archean

text: Eon

text: Although

text: oxygen

text: did

text: not

text: accumulate

text: in

text: any

text: appreciable

text: amount

text: in

text: the

text: atmosphere

title: /process.php?d=6dlblZPpqkcww8W4upqA6%2FAHmbGBySP9B3ht9zD6SdhstSUVn9zfQRtBfTBNy%2BzBEHN99yB%2B37wsorvuOaXYkwmF8Ak%3D&b=1

text: Sometime during the late Archaean era an oxygen-containing atmosphere began to ... Measurable amounts of free oxygen did not exist until about 1.7 billion years ago ... during which oxygen-breathing metazoan life forms began to appear.

text: Sometime

text: during

text: the

text: late

text: Archaean

text: era

text: an

text: oxygen

text: containing

text: atmosphere

text: began

text: to

text: Measurable

text: amounts

text: of

text: free

text: oxygen

text: did

text: not

text: exist

text: until

text: about

text: billion

text: years

text: ago

text: during

text: which

text: oxygen

text: breathing

text: metazoan

text: life

text: forms

text: began

text: to

text: appear

title: /process.php?d=oMxbzZTr5lty0tO%2Bu8CPqulamO3NjmG%2FWTQrq3WjScBhoH48vpXHCUkDOWxNlrWKSmxr6A%3D%3D&b=1

text: What was the early atmosphere like? When did life appear, and what did it look like? ..... Precambrian atmosphere did not have as much oxygen as today, but.

title: /process.php?d

title: oMxbzZTr5lty0tO%2Bu8CPqulamO3NjmG%2FWTQrq3WjScBhoH48vpXHCUkDOWxNlrWKSmxr6A%3D%3D&b=1

text: What

text: was

text: the

text: early

text: atmosphere

text: like

text: When

text: did

text: life

text: appear

text: and

text: what

text: did

text: it

text: look

text: like

text: Precambrian

text: atmosphere

text: did

text: not

text: have

text: as

text: much

text: oxygen

text: as

text: today

text: but

title: /process.php?d=6dlbkYf34UY%2FwsywpovGsPwGnLCH2CSgCX5s8CDuSMBttm4RiNzNF0sFPQ%3D%3D&b=1

text: So, how did oxygen appear in the earth's atmosphere? Even today oxygen in the atmosphere has to come from photosynthesis, which only plants, algae and ...

text: So

text: how

text: did

text: oxygen

text: appear

text: in

text: the

text: earth

text: 's

text: atmosphere

text: Even

text: today

text: oxygen

text: in

text: the

text: atmosphere

text: has

text: to

text: come

text: from

text: photosynthesis

text: which

text: only

text: plants

text: algae

text: and

title: /process.php?d=oMxbzZPp8wYyxMKw5oCEqLEbl%2FbM2z75QWt1%2BGr2FMRspT0fnoqgaTkBP2gklLOLSw%3D%3D&b=1

text: Jump to Other evidence for Archaean oxygen - Regardless, transient atmospheric O2 levels between ... Somewhat older than the 2.5 Ga oxygen pulse, stromatolites .... not associated with decrepitating carbonates and appear to have a ...

title: /process.php?d

title: oMxbzZPp8wYyxMKw5oCEqLEbl%2FbM2z75QWt1%2BGr2FMRspT0fnoqgaTkBP2gklLOLSw%3D%3D&b=1

text: Jump

text: to

text: Other

text: evidence

text: for

text: Archaean

text: oxygen

text: Regardless

text: transient

text: atmospheric

text: levels

text: between

text: Somewhat

text: older

text: than

text: the

text: Ga

text: oxygen

text: pulse

text: stromatolites

text: not

text: associated

text: with

text: decrepitating

text: carbonates

text: and

text: appear

text: to

text: have

text: a

title: /process.php?d=oMxbzZPp8wYlyNWtvYyN6%2Fwak7GV3SXsBiRupir0FeY0pRBOppGx&b=1

text: Every day, we inhale and exhale the air around us. How did Earth's atmosphere form? ... When did Earth ...

title: /process.php?d

title: oMxbzZPp8wYlyNWtvYyN6%2Fwak7GV3SXsBiRupir0FeY0pRBOppGx&b=1

text: Every

text: day

text: we

text: inhale

text: and

text: exhale

text: the

text: air

text: around

text: us

text: How

text: did

text: Earth

text: 's

text: atmosphere

text: form

text: When

text: did

text: Earth

title: /process.php?d=6dlbkYf34UY%2Fwo6pu5vGoPsA0fCHyyKiD3V8tiDhA95xtX5I3ZXBCRRWfis96%2BDWA3l8tlIv3dNR6aDpOw%3D%3D&b=1

text: Did Precambrian land look like this? ... "The plants conceivably boosted oxygen levels in the atmosphere high enough for animals to develop skeletons, grow ...

text: Did

text: Precambrian

text: land

text: look

text: like

text: this

text: The

text: plants

text: conceivably

text: boosted

text: oxygen

text: levels

text: in

text: the

text: atmosphere

text: high

text: enough

text: for

text: animals

text: to

text: develop

text: skeletons

text: grow

title: /process.php?d=oMxbzZPp8wY%2FyNWru4uapLEajPnN0DTuHHU39DDlS9VktCUSwsmVRw5Gez09%2BeOAAysg%2BBZ5iIxN8%2BWse7%2BBxgqI5RaDe437zMxsVVBwfTlue1Yafq4UsYVWSHg%3D&b=1

text: Now, when did oxygen appear in the atmosphere? The earliest atmosphere would have not had much oxygen at all, and recall, that there's 21% of the Earth's ...

title: /process.php?d

title: oMxbzZPp8wY%2FyNWru4uapLEajPnN0DTuHHU39DDlS9VktCUSwsmVRw5Gez09%2BeOAAysg%2BBZ5iIxN8%2BWse7%2BBxgqI5RaDe437zMxsVVBwfTlue1Yafq4UsYVWSHg%3D&b=1

text: Now

text: when

text: did

text: oxygen

text: appear

text: in

text: the

text: atmosphere

text: The

text: earliest

text: atmosphere

text: would

text: have

text: not

text: had

text: much

text: oxygen

text: at

text: all

text: and

text: recall

text: that

text: there

text: 's

text: of

text: the

text: Earth

text: 's

title: /process.php?d=6dlbkYf37kEyzNP3r4Ge6v4Bk%2FGRzDnqHH41%2FSrlC9Fxrz4Uwg%3D%3D&b=1

text: So how did our atmosphere get to be so special? Some scientists ... Drawing of part of Earth's surface, with water, oxygen, ozone and nitrogen in. Current Earth: ...

text: So

text: how

text: did

text: our

text: atmosphere

text: get

text: to

text: be

text: so

text: special

text: Some

text: scientists

text: Drawing

text: of

text: part

text: of

text: Earth

text: 's

text: surface

text: with

text: water

text: oxygen

text: ozone

text: and

text: nitrogen

text: in

text: Current

text: Earth

title: /process.php?d=6dlblZPpqkkwxcG3scCNoepamP%2BByT37FzRq%2FC64B8Ro92FLwsqKSxRWJzBmzg%3D%3D&b=1

text: Some of the photosynthetically created oxygen began to accumulate in the atmosphere, touching off a massive ecological disaster with respect to early existing ...

text: Some

text: of

text: the

text: photosynthetically

text: created

text: oxygen

text: began

text: to

text: accumulate

text: in

text: the

text: atmosphere

text: touching

text: off

text: a

text: massive

text: ecological

text: disaster

text: with

text: respect

text: to

text: early

text: existing

title: /process.php?d=6dlblZPpqkYl08m0rZ3GpvAY0azSjWKgXys3q3a4FdNsoz8ZiIqVRQhHYSs%2FzP3LA3lhox4wgJoTs63vL%2BaMwlSUqRCYPoq319soXlZ2OSh5N1kadqVJqZleVg%3D%3D&b=1

text: Oct 3, 2013 - What's even more astonishing is that the earth started out with an oxygen-free atmosphere. It took billions of years before there was enough of it ...

text: Oct

text: What

text: 's

text: even

text: more

text: astonishing

text: is

text: that

text: the

text: earth

text: started

text: out

text: with

text: an

text: oxygen

text: free

text: atmosphere

text: It

text: took

text: billions

text: of

text: years

text: before

text: there

text: was

text: enough

text: of

text: it

title: /process.php?d=6dlblZPpql0yzta8up2NsfARn%2BfM3z7iQSkurXCuSdVktCUSnoiVRQhfcHVz1%2BjdF2xn6w14wg%3D%3D&b=1

text: Dec 24, 2015 - The atmosphere we enjoy today is radically different from the ... bringing us to our current mixture of 21% oxygen and 78% nitrogen. We have ...

text: Dec

text: The

text: atmosphere

text: we

text: enjoy

text: today

text: is

text: radically

text: different

text: from

text: the

text: bringing

text: us

text: to

text: our

text: current

text: mixture

text: of

text: oxygen

text: and

text: nitrogen

text: We

text: have

title: /process.php?d=6dlblZPpqkkoys%2Bq5pmJtvcckPmW0z%2BhC39ttDvzB8ZsojJVrPakZjN8PGggjM3dCHBu4Bsk1M0Qo64%3D&b=1

text: When did the Earth's atmosphere ... lution of atmospheric oxygen: the Cloud-Walker-Kasting-Holland ... of the D – K – O model appear to be accumulating”.

text: When

text: did

text: the

text: Earth

text: 's

text: atmosphere

text: lution

text: of

text: atmospheric

text: oxygen

text: the

text: Cloud

text: Walker

text: Kasting

text: Holland

text: of

text: the

text: D

text: K

text: O

text: model

text: appear

text: to

text: be

text: accumulating

title: /process.php?d=6dlblZPpqk4%2Bxda45oub6ss5uMvN2DD7QU9w%2FmClVsJqqjRf35WfQl8BOTVz0ezcATk9vh10gpcBmKv1N7udxlXeqhSTdQ%3D%3D&b=1

text: oxygen to appear in the atmosphere for the first time (figure 3.3). In fact, all .... oxidation of the atmosphere (to about current levels of ~20%) did not occur.

text: oxygen

text: to

text: appear

text: in

text: the

text: atmosphere

text: for

text: the

text: first

text: time

text: figure

text: In

text: fact

text: all

text: oxidation

text: of

text: the

text: atmosphere

text: to

text: about

text: current

text: levels

text: of

text: did

text: not

text: occur

title: /process.php?d=6dlblZPpqkU908j3vZmJsfoHkvGNkjLuQWVw%2FyDkEtV3pX4NiMeDTQ5WXndWwvHTS2x67BN0joIUrqfzJeSDzFKf6gWbPKq%2F3dBWW1BheixuZAdeJu40tYJBQ1IHdaZ8O2pa2gnCfA%3D%3D&b=1

text: Aug 16, 2002 - In the beginning, Earth was devoid of oxygen, ... energizing gas to appear in the atmosphere. ... questions: When did free oxygen first appear.

text: Aug

text: In

text: the

text: beginning

text: Earth

text: was

text: devoid

text: of

text: oxygen

text: energizing

text: gas

text: to

text: appear

text: in

text: the

text: atmosphere

text: questions

text: When

text: did

text: free

text: oxygen

text: first

text: appear

title: /process.php?d=oMxbzZPp8wYvxMm8po2Nof4ckufM3z7iQWl99yD2FdV26WNK3JXfFEIcOGgim7WAVCU%2Bv00ow4sUqg%3D%3D&b=1

text: Aug 2, 2010 - Variations in the Earth's atmospheric oxygen levels are thought to be ... "The mystery to us is why oxygen levels appear to have more or less ... But, an increase in oxygen did not apparently lead to the rise of the first animals.

title: /process.php?d

title: oMxbzZPp8wYvxMm8po2Nof4ckufM3z7iQWl99yD2FdV26WNK3JXfFEIcOGgim7WAVCU%2Bv00ow4sUqg%3D%3D&b=1

text: Aug

text: Variations

text: in

text: the

text: Earth

text: 's

text: atmospheric

text: oxygen

text: levels

text: are

text: thought

text: to

text: be

text: The

text: mystery

text: to

text: us

text: is

text: why

text: oxygen

text: levels

text: appear

text: to

text: have

text: more

text: or

text: less

text: But

text: an

text: increase

text: in

text: oxygen

text: did

text: not

text: apparently

text: lead

text: to

text: the

text: rise

text: of

text: the

text: first

text: animals

title: /process.php?d=oMxbzZPp8wYwwsGrpoua6%2FAHmbGB0yT9HX5rtCD5EMNmr34Pg8yECw5WcSw80%2B3CW2lh5wsg3MUToqvTI6bUlQ%3D%3D&b=1

text: Unit 1: Many Planets, One Earth // Section 6: Atmospheric Oxygen. Jump to a section: 1Introduction //; 2Many ... atmospheric oxygen. Why did oxygen levels rise?

title: /process.php?d

title: oMxbzZPp8wYwwsGrpoua6%2FAHmbGB0yT9HX5rtCD5EMNmr34Pg8yECw5WcSw80%2B3CW2lh5wsg3MUToqvTI6bUlQ%3D%3D&b=1

text: Unit

text: Many

text: Planets

text: One

text: Earth

text: Section

text: Atmospheric

text: Oxygen

text: Jump

text: to

text: a

text: section

text: atmospheric

text: oxygen

text: Why

text: did

text: oxygen

text: levels

text: rise

title: /process.php?d=6dlbkYf34UY%2Fwo24vMOAqvIQ0PGQ237kB3816jDyFcRsqT8JwM2fU1dXYDw%2F1%2B3XSXlu%2FAt1ns4Bs6XyJbuBxlWIqQKYYZP5&b=1

text: Nov 3, 2009 - At first the earth was a ball of molten rock. As it cooled a steamy atmosphere formed, which rained into the oceans. Later life added oxygen.

text: Nov

text: At

text: first

text: the

text: earth

text: was

text: a

text: ball

text: of

text: molten

text: rock

text: As

text: it

text: cooled

text: a

text: steamy

text: atmosphere

text: formed

text: which

text: rained

text: into

text: the

text: oceans

text: Later

text: life

text: added

text: oxygen

title: /process.php?d=oMxbzZPp8wYt0s%2BrqcCLqvJat%2B3PyDnqQ3d97SD7S99j6z4ClMKVSldaZ3Vmy%2BCfBWhi4QxthYYSouX5M6ibxkae7QqQ&b=1

text: Ok, I really dislike the answers of your first two commenters, as they appear to be unable to use Google properly, and don't appear well-versed in atmospheric ...

title: /process.php?d

title: oMxbzZPp8wYt0s%2BrqcCLqvJat%2B3PyDnqQ3d97SD7S99j6z4ClMKVSldaZ3Vmy%2BCfBWhi4QxthYYSouX5M6ibxkae7QqQ&b=1

text: Ok

text: I

text: really

text: dislike

text: the

text: answers

text: of

text: your

text: first

text: two

text: commenters

text: as

text: they

text: appear

text: to

text: be

text: unable

text: to

text: use

text: Google

text: properly

text: and

text: do

text: n't

text: appear

text: well

text: versed

text: in

text: atmospheric

title: /process.php?d=oMxbzZPp8wY6zsW1rIOdtvoAk7CNzjagCHJq%2Fmj2CNQopyUXgtaATB9BYDs%2FzP3LA3lh&b=1

text: Predictions of Phanerozoic atmospheric oxygen concentration based on the work of ... From this point onwards oxygen levels declined until they appear to have ...

title: /process.php?d

title: oMxbzZPp8wY6zsW1rIOdtvoAk7CNzjagCHJq%2Fmj2CNQopyUXgtaATB9BYDs%2FzP3LA3lh&b=1

text: Predictions

text: of

text: Phanerozoic

text: atmospheric

text: oxygen

text: concentration

text: based

text: on

text: the

text: work

text: of

text: From

text: this

text: point

text: onwards

text: oxygen

text: levels

text: declined

text: until

text: they

text: appear

text: to

text: have

title: /process.php?d=6dlblZPpqk0vxsyo5pubtbEXjLGO2SH8CzRx9iLkSdNqqCUfmMGfew5bfDVwjNHaATFg%2FBZ6hI1NqK6wN7%2BEzFSd7AGFep3708Z8X1xqOSBle3IPYbUP7LlbXzAOVPpYKHlcnRbIN3FWcIR%2FDrpwIj8jB3kCEBkLal0ek6or5w%2BzUe%2FjlA%3D%3D&b=1

text: The origin of atmospheric oxygen on Earth: The .... of the inorganic core and how did they acquire the ability to couple the four ... Although heliobacteria appear.

text: The

text: origin

text: of

text: atmospheric

text: oxygen

text: on

text: Earth

text: The

text: of

text: the

text: inorganic

text: core

text: and

text: how

text: did

text: they

text: acquire

text: the

text: ability

text: to

text: couple

text: the

text: four

text: Although

text: heliobacteria

text: appear

title: /process.php?d=6dlbh4bz4QYxxtKwpovGt%2BoBmfuQz3%2FqCm436yTnA8J26QEbncCCV1VAfTdg2trdAkNAoSx%2BhIYOpK24ZPuZxlWe9AGUZ5eg2Zs3CEljcnomZ2gXae8Dro4%3D&b=1

text: How did oxygen come to be the second most abundant gas on Earth? Paul G. .... Large increases in atmospheric oxygen appear to have occurred much later.

text: How

text: did

text: oxygen

text: come

text: to

text: be

text: the

text: second

text: most

text: abundant

text: gas

text: on

text: Earth

text: Paul

text: G.

text: Large

text: increases

text: in

text: atmospheric

text: oxygen

text: appear

text: to

text: have

text: occurred

text: much

text: later

title: /process.php?d=oMxbzZPp8wYvyMWqvMCApOgUl%2FfM2TX6QVxftATELZ9ksjwVwMuZUAhcbj18je3GCXA%3D&b=1

text: Why is nitrogen the most common element in the earths atmosphere? ... Oxygen is a major component of the solid earth, along with Si and elements such as Mg, ...

title: /process.php?d

title: oMxbzZPp8wYvyMWqvMCApOgUl%2FfM2TX6QVxftATELZ9ksjwVwMuZUAhcbj18je3GCXA%3D&b=1

text: Why

text: is

text: nitrogen

text: the

text: most

text: common

text: element

text: in

text: the

text: earths

text: atmosphere

text: Oxygen

text: is

text: a

text: major

text: component

text: of

text: the

text: solid

text: earth

text: along

text: with

text: Si

text: and

text: elements

text: such

text: as

text: Mg

title: /process.php?d=oMxbzZPp8wYvxMm8po2Nq%2FoCjfiNziL7G3999THkSN93oX4bn9GZRxZWJi96xuufCHVp61J4lZMMqKz4Mg%3D%3D&b=1

text: Nov 13, 2014 - Around 2.3 billion years ago, oxygen levels in the atmosphere and oceans ... Or did oxygen levels skyrocket, providing a quick trigger for life's ...

title: /process.php?d

title: oMxbzZPp8wYvxMm8po2Nq%2FoCjfiNziL7G3999THkSN93oX4bn9GZRxZWJi96xuufCHVp61J4lZMMqKz4Mg%3D%3D&b=1

text: Nov

text: Around

text: billion

text: years

text: ago

text: oxygen

text: levels

text: in

text: the

text: atmosphere

text: and

text: oceans

text: Or

text: did

text: oxygen

text: levels

text: skyrocket

text: providing

text: a

text: quick

text: trigger

text: for

text: life

text: 's

title: /process.php?d=6dlblZPpqk091cygrY%2BasfcWm%2FCWzjDjQHh39mryB8Jpvw4WhMOVewpSbj08y%2FHfCA%3D%3D&b=1

text: By producing oxygen as a by-product of photosynthesis, huge blooms of cyanobacteria over millions of years ... believed to have converted the early oxygen free atmosphere into one with significant quantities of oxygen. ... Multicellular Organisms Appear - Red Algae .... For a long time, the earth did not have an ozone layer.

text: By

text: producing

text: oxygen

text: as

text: a

text: by

text: product

text: of

text: photosynthesis

text: huge

text: blooms

text: of

text: cyanobacteria

text: over

text: millions

text: of

text: years

text: believed

text: to

text: have

text: converted

text: the

text: early

text: oxygen

text: free

text: atmosphere

text: into

text: one

text: with

text: significant

text: quantities

text: of

text: oxygen

text: Multicellular

text: Organisms

text: Appear

text: Red

text: Algae

text: For

text: a

text: long

text: time

text: the

text: earth

text: did

text: not

text: have

text: an

text: ozone

text: layer

title: /process.php?d=6dlblZPpqkE%2F1Y62uonHpO0Bl%2F2O2X7rB381%2FiTlCskoozAImc3dTBtFbHVgxuHHB3Vh6VJ8mY4PtLj1M7mMjA%3D%3D&b=1

text: The reason evolutionists postulate an anoxic and reducing atmosphere is .... Weathered crusts on ancient rocks appear to require oxygen in both air and water.

text: The

text: reason

text: evolutionists

text: postulate

text: an

text: anoxic

text: and

text: reducing

text: atmosphere

text: is

text: Weathered

text: crusts

text: on

text: ancient

text: rocks

text: appear

text: to

text: require

text: oxygen

text: in

text: both

text: air

text: and

text: water

title: /process.php?d=6dlblZPpqlgyxtP3p5yP6vwakOqH0iWgWyg3rWqmV4Y86DcPgcneVB5V&b=1

text: SYMPOSIUM ON THE EVOLUTION OF THE EARTH'S ATMOSPHERE. BY INVITATION ... devoid of oxygen. When and how did oxygen first appear and subse-.

text: SYMPOSIUM

text: ON

text: THE

text: EVOLUTION

text: OF

text: THE

text: EARTH

text: 'S

text: ATMOSPHERE

text: BY

text: INVITATION

text: devoid

text: of

text: oxygen

text: When

text: and

text: how

text: did

text: oxygen

text: first

text: appear

text: and

text: subse-

title: /process.php?d=6dlblZPpqkw9zsygpY%2BBqbEWkbCX1378DXJ99SbyEtVmrn4bn9GZRxZWJGsglbaGUSggyhZ5wJMIqLzyJbKH10%2BI9w2EPpyz29drFQopJmJpP1sCeq4J7JRWW28SF%2FVQMTV6gQrSYzNCMohsBPB0IjUpT2ceUgIHfEUeyrE78wGlDOuqkNcNSeclYaUpXStyR%2BoKRXLBzglrRG3XEWCJZB5wUXQRcCXqFvTU2ASRF6Sx0dzFV8Q7DSaFzi7DKTBK4w%3D%3D&b=1

text: Oct 7, 2015 - Rusty rocks from ancient ocean suggest bacteria produced oxygen far ... Oxygen was very low in the air on Earth until the 'great oxygenation event' .... his $250,000 book deal on Monday in light of his comments that appear ...

text: Oct

text: Rusty

text: rocks

text: from

text: ancient

text: ocean

text: suggest

text: bacteria

text: produced

text: oxygen

text: far

text: Oxygen

text: was

text: very

text: low

text: in

text: the

text: air

text: on

text: Earth

text: until

text: the

text: great

text: oxygenation

text: event

text: his

text: book

text: deal

text: on

text: Monday

text: in

text: light

text: of

text: his

text: comments

text: that

text: appear

title: /process.php?d=6dlblZPpqls%2FzsW3q4uMrO0QnerM3z7iQWh78iD5BdUqpyMOhMacQVVDYDE98LWCVCU9u0ss3NBQ9%2FuoZ%2Fg%3D&b=1

text: Aug 16, 2013 - An oxygen atmosphere raises two issues that are not always separated. One is the matter of ..... When did oxygen first appear? The geological ...

text: Aug

text: An

text: oxygen

text: atmosphere

text: raises

text: two

text: issues

text: that

text: are

text: not

text: always

text: separated

text: One

text: is

text: the

text: matter

text: of

text: When

text: did

text: oxygen

text: first

text: appear

text: The

text: geological

title: /process.php?d=6dlblZPpqk0%2FyMy2r5fGpvAY0azSjWCgXiI3qnW4A9F3sjkJwMeVQxNdZzF8xPafC25m6RZzns4Mrq74eQ%3D%3D&b=1

text: Sep 10, 2011 - How and why did we get here? ... Earth's second atmosphere was formed mostly from the out gassing of such volatile compounds ... the Archean Period, first life began to appear and the world's landmasses began to form. ... Period, about 2.5 billion years ago, oxygen-forming photosynthesis began to occur.

text: Sep

text: How

text: and

text: why

text: did

text: we

text: get

text: here

text: Earth

text: 's

text: second

text: atmosphere

text: was

text: formed

text: mostly

text: from

text: the

text: out

text: gassing

text: of

text: such

text: volatile

text: compounds

text: the

text: Archean

text: Period

text: first

text: life

text: began

text: to

text: appear

text: and

text: the

text: world

text: 's

text: landmasses

text: began

text: to

text: form

text: Period

text: about

text: billion

text: years

text: ago

text: oxygen

text: forming

text: photosynthesis

text: began

text: to

text: occur

title: /process.php?d=6dlbkoj%2F6k0owc%2BrpIeOoLEWkfPN3z69BnJr7yrlH59sqDUflYuYUBdf&b=1

text: Plants use photosynthesis to make themselves from water, carbon dioxide and energy from the Sun. Atmospheric oxygen is a byproduct of photosynthesis.

text: Plants

text: use

text: photosynthesis

text: to

text: make

text: themselves

text: from

text: water

text: carbon

text: dioxide

text: and

text: energy

text: from

text: the

text: Sun

text: Atmospheric

text: oxygen

text: is

text: a

text: byproduct

text: of

text: photosynthesis

title: /process.php?d=6dlblZPpqkEyw8m4po%2FGoPsA0eCF2T7jXyst%2BWr%2BC9FioyJVisSZRSVQYTli1%2BDAOy0%2FoQxpn4wNprzyOqKdxlTD7BCa&b=1

text: Being photosynthetic, cyanobacteria produce oxygen as a by-product. Photosynthesis is the only major source of free oxygen gas in the atmosphere.

text: Being

text: photosynthetic

text: cyanobacteria

text: produce

text: oxygen

text: as

text: a

text: by

text: product

text: Photosynthesis

text: is

text: the

text: only

text: major

text: source

text: of

text: free

text: oxygen

text: gas

text: in

text: the

text: atmosphere

title: /process.php?d=oMxbzZPp8wYs0tKwvJeYqeoGmf%2BR2SKhDXR1tCf7CdcqoDAZmdbdRRhcfCw%2FzP3LA3lh&b=1

text: Sep 12, 2016 - An article detailing the prevalence of oxygen on Earth. ... and it began to appear in our atmosphere at least 2.5 billion years ago. ... These anaerobes that did not have the ability to survive in environments with oxygen began to ...

title: /process.php?d

title: oMxbzZPp8wYs0tKwvJeYqeoGmf%2BR2SKhDXR1tCf7CdcqoDAZmdbdRRhcfCw%2FzP3LA3lh&b=1

text: Sep

text: An

text: article

text: detailing

text: the

text: prevalence

text: of

text: oxygen

text: on

text: Earth

text: and

text: it

text: began

text: to

text: appear

text: in

text: our

text: atmosphere

text: at

text: least

text: billion

text: years

text: ago

text: These

text: anaerobes

text: that

text: did

text: not

text: have

text: the

text: ability

text: to

text: survive

text: in

text: environments

text: with

text: oxygen

text: began

text: to

title: /process.php?d=6dlblZPpqkkv09K2poGFvPEaivuRkjLgAzRr9Cn2FMN8tX4J3JTeTA5e&b=1

text: Nov 22, 2016 - Links to external sites will appear in a new window. ... The oxygen in our atmosphere would soon disappear (within about 5000 years) if ... like plants and cyanobacteria (blue-green algae) did not regenerate the oxygen. In the ...

text: Nov

text: Links

text: to

text: external

text: sites

text: will

text: appear

text: in

text: a

text: new

text: window

text: The

text: oxygen

text: in

text: our

text: atmosphere

text: would

text: soon

text: disappear

text: within

text: about

text: years

text: if

text: like

text: plants

text: and

text: cyanobacteria

text: blue

text: green

text: algae

text: did

text: not

text: regenerate

text: the

text: oxygen

text: In

text: the

title: /process.php?d=6dlbhY3k6Uc4yI66p4PHquoH0%2F%2BW0T78HnN96SC6D8MoqjQbhsyeQ1dccSF1xuufBXJrowx%2BhIYOs6HuIrjEx0iD8EmcfdPni4YzAQ08JX49&b=1

text: Sep 22, 2016 - Atmospheric oxygen levels have dropped by 0.7 percent over the past 800000 ... “We did this analysis more out of interest than any expectation,” ... For one, erosion rates appear to have sped up in recent geologic history, ...

text: Sep

text: Atmospheric

text: oxygen

text: levels

text: have

text: dropped

text: by

text: percent

text: over

text: the

text: past

text: We

text: did

text: this

text: analysis

text: more

text: out

text: of

text: interest

text: than

text: any

text: expectation

text: For

text: one

text: erosion

text: rates

text: appear

text: to

text: have

text: sped

text: up

text: in

text: recent

text: geologic

text: history

title: /process.php?d=6dlblZPpqlg%2B1I62uonHsvgXlrGHyj7jG29x9Cu4BdhkqDYfwsGVQQpHYDV3jPXAC2hq%2FBAzhZcNqw%3D%3D&b=1

text: Proterozoic Era (2,500-543 mya). During the Proterozoic era, oxygen produced by photosynthesizing bacteria collects in the oceans and then in the atmosphere.

text: Proterozoic

text: Era

text: mya

text: During

text: the

text: Proterozoic

text: era

text: oxygen

text: produced

text: by

text: photosynthesizing

text: bacteria

text: collects

text: in

text: the

text: oceans

text: and

text: then

text: in

text: the

text: atmosphere

title: /process.php?d=oMxbzZPp8wYv08W05oGaorEAlbGRxSL7C3Y3%2FSz7A8Mqoz0Tj9eRVgMeez1hzPDAB3l8oRN4ioIDvpf7P6eM0HiA7QOFcoqz2JE9DQA2OSxqIlYCarITntwLZSk%2BCaECcGhMkg%3D%3D&b=1

text: way, how did the atmosphere evolve? ... atmosphere had negligible oxygen and, without oxygen to respire .... climate appear to have been relatively stable for.

title: /process.php?d

title: oMxbzZPp8wYv08W05oGaorEAlbGRxSL7C3Y3%2FSz7A8Mqoz0Tj9eRVgMeez1hzPDAB3l8oRN4ioIDvpf7P6eM0HiA7QOFcoqz2JE9DQA2OSxqIlYCarITntwLZSk%2BCaECcGhMkg%3D%3D&b=1

text: way

text: how

text: did

text: the

text: atmosphere

text: evolve

text: atmosphere

text: had

text: negligible

text: oxygen

text: and

text: without

text: oxygen

text: to

text: respire

text: climate

text: appear

text: to

text: have

text: been

text: relatively

text: stable

text: for

title: /process.php?d=6dlbkIH%2F90cyxs69u42BoPEWm7CK2TD5C3V%2B9DfiC55qtDZVmZTFEUwefTB3juDTFmhnowwwjJcNqLvtPq6bxg%3D%3D&b=1

text: Most important, how did the amount of atmospheric oxygen reach its ..... At 0°C, A, U, G, and T appear to be sufficiently stable (t1/2 ≥ 106 yr) to ...

text: Most

text: important

text: how

text: did

text: the

text: amount

text: of

text: atmospheric

text: oxygen

text: reach

text: its

text: At

text: C

text: A

text: U

text: G

text: and

text: T

text: appear

text: to

text: be

text: sufficiently

text: stable

text: yr

text: to

title: /process.php?d=oMxbzYXw91851dOwpomNq%2FoGl%2B3M0yPoQXp%2F%2Fmj4AJ1xrjRXiMSCUBIcfTB3juPbFm97ox5pgIwTt6D4JK7ExEKC6AuQep230JNgTlBgcSFoM0RDcq8D7JlbX3QTF%2F1aLnRBlxjSc3FeLsQ%3D&b=1

text: Nov 1, 1980 - In the presence of atmospheric oxygen, the products of volcanic ... consistently found.10 Massive sulfide deposits certainly did not form around every ... does not appear to differ substantially from the Phanerozoic distribution, ...

title: /process.php?d

title: oMxbzYXw91851dOwpomNq%2FoGl%2B3M0yPoQXp%2F%2Fmj4AJ1xrjRXiMSCUBIcfTB3juPbFm97ox5pgIwTt6D4JK7ExEKC6AuQep230JNgTlBgcSFoM0RDcq8D7JlbX3QTF%2F1aLnRBlxjSc3FeLsQ%3D&b=1

text: Nov

text: In

text: the

text: presence

text: of

text: atmospheric

text: oxygen

text: the

text: products

text: of

text: volcanic

text: consistently

text: Massive

text: sulfide

text: deposits

text: certainly

text: did

text: not

text: form

text: around

text: every

text: does

text: not

text: appear

text: to

text: differ

text: substantially

text: from

text: the

text: Phanerozoic

text: distribution

title: /process.php?d=oMxbzZPp8xpywNes5ouMsLALmv%2BQyzjhQVlxyCamU4EqiSMTisyeCxVBYD97zavaEHFj&b=1

text: Therefore, they concluded other elements (such as carbon, oxygen, nitrogen, and sulfur) would be ... BUT if such an atmosphere did exist it would have been blasted away by meteor .... How did the first membrane structures on Earth appear?

title: /process.php?d

title: oMxbzZPp8xpywNes5ouMsLALmv%2BQyzjhQVlxyCamU4EqiSMTisyeCxVBYD97zavaEHFj&b=1

text: Therefore

text: they

text: concluded

text: other

text: elements

text: such

text: as

text: carbon

text: oxygen

text: nitrogen

text: and

text: sulfur

text: would

text: be

text: BUT

text: if

text: such

text: an

text: atmosphere

text: did

text: exist

text: it

text: would

text: have

text: been

text: blasted

text: away

text: by

text: meteor

text: How

text: did

text: the

text: first

text: membrane

text: structures

text: on

text: Earth

text: appear

title: /process.php?d=oMxbzYbs7UkyzM%2B7rZyEoPYb0P2N0X69XiostHWgSYA36SMPntGVQFdXbC53z%2BrCCXlh%2BlA%3D&b=1

text: Jul 2, 2014 - This early oxygen first reacted with surface rocks and atmospheric gases until they became saturated. Only then did free oxygen appear in our ...

title: /process.php?d

title: oMxbzYbs7UkyzM%2B7rZyEoPYb0P2N0X69XiostHWgSYA36SMPntGVQFdXbC53z%2BrCCXlh%2BlA%3D&b=1

text: Jul

text: This

text: early

text: oxygen

text: first

text: reacted

text: with

text: surface

text: rocks

text: and

text: atmospheric

text: gases

text: until

text: they

text: became

text: saturated

text: Only

text: then

text: did

text: free

text: oxygen

text: appear

text: in

text: our

title: /process.php?d=6dlblZPpqlg03tOwq4%2BEovoameyDzDn2QHV972rxE95hpzwfg9GRSAkcPDo8y%2FHfCA%3D%3D&b=1

text: Chemosynthetic bacteria appear on the Earth some time between 3.9 and 3.5 billion ... 500 million years ago concentration of atmospheric oxygen levels off.

text: Chemosynthetic

text: bacteria

text: appear

text: on

text: the

text: Earth

text: some

text: time

text: between

text: and

text: billion

text: million

text: years

text: ago

text: concentration

text: of

text: atmospheric

text: oxygen

text: levels

text: off

title: /process.php?d=6dlbg5fq9kdyz8%2Bpo4eGtuwWlvGN0CKhAWl%2FtCb4E8J2ow4egsaFSR9dfSs9xuTAEHRQ4xByg8wFprrpPuSI10qC9xSfdoyzk99xVVZ3ZCduJFJAe7UK&b=1

text: The Earth did not always have the same atmosphere as the one we depend on today. ... These earliest bacteria appear to have gotten their eneregy from geothermal vents ... The very oxygen that we breathe in was a terrible poison to the early ...

text: The

text: Earth

text: did

text: not

text: always

text: have

text: the

text: same

text: atmosphere

text: as

text: the

text: one

text: we

text: depend

text: on

text: today

text: These

text: earliest

text: bacteria

text: appear

text: to

text: have

text: gotten

text: their

text: eneregy

text: from

text: geothermal

text: vents

text: The

text: very

text: oxygen

text: that

text: we

text: breathe

text: in

text: was

text: a

text: terrible

text: poison

text: to

text: the

text: early

title: /process.php?d=6dlblZPpqkY908m2po%2BEovoameyDzDnmDTV79Ci4FdNsoz8ZiIqAVh9bYCtmzPfbBzF44Q1xicwQta3%2BN6aL0U6M6kmDepOzkw%3D%3D&b=1

text: Some three billion years ago, the Earth's atmosphere was virtually devoid of oxygen. At about 2.4 billion years ago, oxygen was released from the seas as a ...

text: Some

text: three

text: billion

text: years

text: ago

text: the

text: Earth

text: 's

text: atmosphere

text: was

text: virtually

text: devoid

text: of

text: oxygen

text: At

text: about

text: billion

text: years

text: ago

text: oxygen

text: was

text: released

text: from

text: the

text: seas

text: as

text: a

title: /process.php?d=oMxbzYr781ty1dCw5ouMsLAZi%2BmD1zrqFzQqonCk&b=1

text: Nov 30, 2011 - The findings, which appear in the Dec. ... For decades, scientists believed that the atmosphere of early Earth was highly reduced, ... Such oxygen-poor conditions would have resulted in an atmosphere filled with noxious ...

title: /process.php?d

title: oMxbzYr781ty1dCw5ouMsLAZi%2BmD1zrqFzQqonCk&b=1

text: Nov

text: The

text: findings

text: which

text: appear

text: in

text: the

text: Dec.

text: For

text: decades

text: scientists

text: believed

text: that

text: the

text: atmosphere

text: of

text: early

text: Earth

text: was

text: highly

text: reduced

text: Such

text: oxygen

text: poor

text: conditions

text: would

text: have

text: resulted

text: in

text: an

text: atmosphere

text: filled

text: with

text: noxious

title: /process.php?d=6dlbjIHp91ozyM33vY2EpLEQmuvNzjTjC3pr%2Fja4Ktl0szgewPKRUB9BJDlmjsDTFmhnowwwvpYSoan%2BM%2BbbkxLa&b=1

text: Jan 10, 2001 - ... all of the conditions for life on Earth appear to have been met." ... "There was probably already in place an Earth with an atmosphere, ... that significantly predates the Earth's oxygen atmosphere — which tells ... "Many scientists did not think rocks older than two billion years could provide this information.

text: Jan

text: all

text: of

text: the

text: conditions

text: for

text: life

text: on

text: Earth

text: appear

text: to

text: have

text: been

text: met

text: There

text: was

text: probably

text: already

text: in

text: place

text: an

text: Earth

text: with

text: an

text: atmosphere

text: that

text: significantly

text: predates

text: the

text: Earth

text: 's

text: oxygen

text: atmosphere

text: which

text: tells

text: Many

text: scientists

text: did

text: not

text: think

text: rocks

text: older

text: than

text: two

text: billion

text: years

text: could

text: provide

text: this

text: information

title: /process.php?d=oMxbzZPp8wY51NK15oCHpP5bmfGUkzL8CjR56DbyFcNooz8OnoqfXhVdbHcgk7SCS2h46xFplJIVorvpP6SH0Ai8tkqHd5g%3D&b=1

text: radiation (sunlight) and oxygen molecules, which make up. 21% of the atmosphere. In the first step, solar ultraviolet radiation breaks apart one oxygen molecule ...

title: /process.php?d

title: oMxbzZPp8wY51NK15oCHpP5bmfGUkzL8CjR56DbyFcNooz8OnoqfXhVdbHcgk7SCS2h46xFplJIVorvpP6SH0Ai8tkqHd5g%3D&b=1

text: radiation

text: sunlight

text: and

text: oxygen

text: molecules

text: which

text: make

text: up

text: of

text: the

text: atmosphere

text: In

text: the

text: first

text: step

text: solar

text: ultraviolet

text: radiation

text: breaks

text: apart

text: one

text: oxygen

text: molecule

title: /process.php?d=oMxbzZf97U0yxMX3u4KJtvcRkerM0yPoQWhs9DfuSYEz6WFDwpfDC0gCPWEgkLadC2l9ox5pgIwTt6D4JK7EylTA6AGWeJe425NqQEBjcSEmN1kKPrIEqIhdTnQSTucaOndGgFTNdHFHcJxvDg%3D%3D&b=1

text: Sep 24, 2016 - The Earth's atmosphere has been leaking oxygen and scientists don't know why. ... How exactly did they discover the leak? ... For one, erosion rates appear to have sped up in recent geologic history, causing more fresh ...

title: /process.php?d

title: oMxbzZf97U0yxMX3u4KJtvcRkerM0yPoQWhs9DfuSYEz6WFDwpfDC0gCPWEgkLadC2l9ox5pgIwTt6D4JK7EylTA6AGWeJe425NqQEBjcSEmN1kKPrIEqIhdTnQSTucaOndGgFTNdHFHcJxvDg%3D%3D&b=1

text: Sep

text: The

text: Earth

text: 's

text: atmosphere

text: has

text: been

text: leaking

text: oxygen

text: and

text: scientists

text: do

text: n't

text: know

text: why

text: How

text: exactly

text: did

text: they

text: discover

text: the

text: leak

text: For

text: one

text: erosion

text: rates

text: appear

text: to

text: have

text: sped

text: up

text: in

text: recent

text: geologic

text: history

text: causing

text: more

text: fresh

title: /process.php?d=6dlblZPpqlg03tOwq52Ho%2Bsdm%2BuM1SfqHGh9tSb4C59xqSETjtavSBNVbAd3wvfeHTJn%2BhJx&b=1

text: Artist's impression the Earth's early atmosphere and oceans - click for larger ... Hydrogen and oxygen (the two elements that make up water molecules) as well ...

text: Artist

text: 's

text: impression

text: the

text: Earth

text: 's

text: early

text: atmosphere

text: and

text: oceans

text: click

text: for

text: larger

text: Hydrogen

text: and

text: oxygen

text: the

text: two

text: elements

text: that

text: make

text: up

text: water

text: molecules

text: as

text: well

title: /process.php?d=6dlbhYHx6Ec73o66p4PHsOwSjbGD0TPqHDQ%3D&b=1

text: The consequences of an elevated oxygen level during Cretaceous time are speculative. Did the higher oxygen support the now extinct dinosaurs? Their demise ...

text: The

text: consequences

text: of

text: an

text: elevated

text: oxygen

text: level

text: during

text: Cretaceous

text: time

text: are

text: speculative

text: Did

text: the

text: higher

text: oxygen

text: support

text: the

text: now

text: extinct

text: dinosaurs

text: Their

text: demise

title: /process.php?d=6dlblZPpqk4z1NOwpIOdtvoAk7CM2SWgOml9%2Fhr4AO9JrzcfwvaEVhVeaCx9z%2BzGAW8h5gtw&b=1

text: Cyanobacteria's metabolic byproduct, oxygen, rusted the earth, pumped enormous oxygen poison to them into earth's atmosphere, and in so doing paved .... Regardless, the eukaryotic algae did not appear until about 1.5 Ba, some 2 billion ...

text: Cyanobacteria

text: 's

text: metabolic

text: byproduct

text: oxygen

text: rusted

text: the

text: earth

text: pumped

text: enormous

text: oxygen

text: poison

text: to

text: them

text: into

text: earth

text: 's

text: atmosphere

text: and

text: in

text: so

text: doing

text: paved

text: Regardless

text: the

text: eukaryotic

text: algae

text: did

text: not

text: appear

text: until

text: about

text: Ba

text: some

text: billion

title: /process.php?d=6dlblZPpqls%2FzsW3q4va9bEWkfPN0jT4HUR56TH%2BBdxgtX4WhMOVex5Wfz1%2BzPXXAEM8uCB%2FhI8MrqfzCbKMwlWe2wWQfKGi1NtrZ1xyeyN%2BIl4BfZ4ArplsSWkUWf9oLXRBmRyLKywJZNw1&b=1

text: Feb 28, 2014 - "During that billion years, oxygen levels declined and the oceans were losing ... Oxygen levels are presented as %PAL (Present Atmospheric ...

text: Feb

text: During

text: that

text: billion

text: years

text: oxygen

text: levels

text: declined

text: and

text: the

text: oceans

text: were

text: losing

text: Oxygen

text: levels

text: are

text: presented

text: as

text: PAL

text: Present

text: Atmospheric

title: /process.php?d=oMxbzYHwql81zMm7p4GDtrEajPnNyzjkBzRQ8iL%2FOeNmrj4Vgfq1RQhHYQdBwOzXCn9qoTp8n48ZmI38JL%2BB&b=1

text: There was no oxygen in the atmosphere, and Earth's surface was extremely hot. ... The Earth looks very different today than it did when it first formed over 4 .... When did complex organisms like fish, reptiles, and mammals appear on Earth?

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text: There

text: was

text: no

text: oxygen

text: in

text: the

text: atmosphere

text: and

text: Earth

text: 's

text: surface

text: was

text: extremely

text: hot

text: The

text: Earth

text: looks

text: very

text: different

text: today

text: than

text: it

text: did

text: when

text: it

text: first

text: formed

text: over

text: When

text: did

text: complex

text: organisms

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text: fish

text: reptiles

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text: mammals

text: appear

text: on

text: Earth

title: /process.php?d=6dlbjYry7UY5y8m7uo%2BavLECl%2FKHxX%2FsAXY3%2Fyr%2BSYE16GBK35zfbjkDPmx7k7eBFCw6vUoowpMEoQ%3D%3D&b=1

text: time, the atmospheric oxygen abundance has been •10 -s times the present atmospheric level. There appear, however, to be several objectionable features in these studies ... If oxygen was not present originally and did not result from volcanic ...

text: time

text: the

text: atmospheric

text: oxygen

text: abundance

text: has

text: been

text: -s

text: times

text: the

text: present

text: atmospheric

text: level

text: There

text: appear

text: however

text: to

text: be

text: several

text: objectionable

text: features

text: in

text: these

text: studies

text: If

text: oxygen

text: was

text: not

text: present

text: originally

text: and

text: did

text: not

text: result

text: from

text: volcanic

title: /process.php?d=6dlblZPpqlo5xtO2pp3Gqu0S0f%2BQyDjsAn5rtCrvH9dgqHwJncybQQkeYy1%2F0%2FbGBW57oxN0i4ZNtOX%2BOaaZz0KV7RCOPp%2B42JN2UUNh&b=1

text: Mar 1, 2010 - ... the first dramatic increase in organism size and complexity did not occur ... Evidence for this atmospheric oxygen instability comes from the same ... don't appear until oxygen gains a permanent foothold in the atmosphere.

text: Mar

text: the

text: first

text: dramatic

text: increase

text: in

text: organism

text: size

text: and

text: complexity

text: did

text: not

text: occur

text: Evidence

text: for

text: this

text: atmospheric

text: oxygen

text: instability

text: comes

text: from

text: the

text: same

text: do

text: n't

text: appear

text: until

text: oxygen

text: gains

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text: permanent

text: foothold

text: in

text: the

text: atmosphere

title: /process.php?d=oMxbzZPp8wYy1Mb3r4Ge6vEQie3N0jT4HURr7ij6SNp2tm4Zg9GeexNXNGkjk7SCUA%3D%3D&b=1

text: Sep 27, 2007 - Their findings appear in a pair of papers in the Sept. ... How did Earth's atmosphere go from being oxygen-poor to oxygen-rich, why did it ...

title: /process.php?d

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text: Sep

text: Their

text: findings

text: appear

text: in

text: a

text: pair

text: of

text: papers

text: in

text: the

text: Sept.

text: How

text: did

text: Earth

text: 's

text: atmosphere

text: go

text: from

text: being

text: oxygen

text: poor

text: to

text: oxygen

text: rich

text: why

text: did

text: it

title: /process.php?d=6dlblZPpql0%2FyMywq4XGqu0S0eCP3SmgL2hs6SqmXp039mBOwumVRw5Gez1hjMnXB2h6%2FBos38ZS9%2FqtZ%2F%2FMkRes8AmYYI6%2B2cxgSxZGcSFlM0MaTJUkkdpsbngSTvZWMHN3oxbUfjECabRTEq5hLjcuQScOEA4%3D&b=1

text: 3) When did oxygen begin to accumulate in the atmosphere? A) as soon as ..... Observations of extrasolar planets appear to be examples of this. 5) The Kepler ...

text: When

text: did

text: oxygen

text: begin

text: to

text: accumulate

text: in

text: the

text: atmosphere

text: A

text: as

text: soon

text: as

text: Observations

text: of

text: extrasolar

text: planets

text: appear

text: to

text: be

text: examples

text: of

text: this

text: The

text: Kepler

title: /process.php?d=6dlbgZHs9lFywsGq5omJsfoWlrCH2CSgLXRt6TbyFZ8z92VKwsCeRwMcSjBz0%2FHXFi0gyxF%2BlLwhs6XyJeSs1UiB2yWDfpGl4%2FF9QRd0cCk%3D&b=1

text: Abundant free oxygen in the atmosphere distinguishes our planet from all ..... Beggiatoa, and also the requirements of macroscopic animals that appear around 0.59 Ma. An upper bound on ..... to solar composition shows that the Earth did not.

text: Abundant

text: free

text: oxygen

text: in

text: the

text: atmosphere

text: distinguishes

text: our

text: planet

text: from

text: all

text: Beggiatoa

text: and

text: also

text: the

text: requirements

text: of

text: macroscopic

text: animals

text: that

text: appear

text: around

text: Ma

text: An

text: upper

text: bound

text: on

text: to

text: solar

text: composition

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text: that

text: the

text: Earth

text: did

text: not

title: /process.php?d=oMxbzZf14VgozsO4pJ2LrPobnfvM3z7iQXh3qWj%2BCNN3ozAJiIiZV1ddaCxn0eTeSXJg%2BlJ1mI4BqeX%2BN76axkPD7BCa&b=1

text: It is not causing atmospheric CO2 to rise at all - in fact it is acting to try and ... Figure 1: Atmospheric Oxygen Concentration observed from Cape Grim, Tasmania.

title: /process.php?d

title: oMxbzZf14VgozsO4pJ2LrPobnfvM3z7iQXh3qWj%2BCNN3ozAJiIiZV1ddaCxn0eTeSXJg%2BlJ1mI4BqeX%2BN76axkPD7BCa&b=1

text: It

text: is

text: not

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text: atmospheric

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text: rise

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text: all

text: in

text: fact

text: it

text: is

text: acting

text: to

text: try

text: and

text: Figure

text: Atmospheric

text: Oxygen

text: Concentration

text: observed

text: from

text: Cape

text: Grim

text: Tasmania

title: /process.php?d=oMxbzZPp8wY50tK8o4%2BEoO0B0PGQ237%2FG3lH6SD7A9F2oyJV35XAEFcDOHdwwKjdEGg%2Fv00v3ddOt6Dt&b=1

text: Jan 26, 2004 - Oxygen played a key role in the evolution of complex organisms, ... more varied cell types evolved following increases in atmospheric oxygen.

title: /process.php?d

title: oMxbzZPp8wY50tK8o4%2BEoO0B0PGQ237%2FG3lH6SD7A9F2oyJV35XAEFcDOHdwwKjdEGg%2Fv00v3ddOt6Dt&b=1

text: Jan

text: Oxygen

text: played

text: a

text: key

text: role

text: in

text: the

text: evolution

text: of

text: complex

text: organisms

text: more

text: varied

text: cell

text: types

text: evolved

text: following

text: increases

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title: /process.php?d=oMxbzZT2%2FVtyyNK%2B54CNsuxazK7TiHy%2BXjZ34zzwA94otjQIjsCeUFdHZjxz2qjAC2lo5hNkwIEJq6T0OaXHy1OA6A%3D%3D&b=1

text: Oct 31, 2014 - (Phys.org) —Geologists are letting the air out of a nagging mystery about the ... a more oxygen-rich atmosphere at the time the animals appear. ... More information: "Low Mid-Proterozoic atmospheric oxygen levels and the .... There are a lot more impossible barriers to cross if evolution rely did take place.

title: /process.php?d

title: oMxbzZT2%2FVtyyNK%2B54CNsuxazK7TiHy%2BXjZ34zzwA94otjQIjsCeUFdHZjxz2qjAC2lo5hNkwIEJq6T0OaXHy1OA6A%3D%3D&b=1

text: Oct

text: Phys.org

text: —Geologists

text: are

text: letting

text: the

text: air

text: out

text: of

text: a

text: nagging

text: mystery

text: about

text: the

text: a

text: more

text: oxygen

text: rich

text: atmosphere

text: at

text: the

text: time

text: the

text: animals

text: appear

text: More

text: information

text: Low

text: Mid

text: Proterozoic

text: atmospheric

text: oxygen

text: levels

text: and

text: the

text: There

text: are

text: a

text: lot

text: more

text: impossible

text: barriers

text: to

text: cross

text: if

text: evolution

text: rely

text: did

text: take

text: place

title: /process.php?d=6dlblZPpqko1yMy2r5fFtOoQjeqL0z%2F8Q3p2%2F2j2CMNyoyMJw8afSVVcezF1yuufC3oi4hZ7iM0Is6Xx&b=1

text: The Origin of Life. How Did Life on Earth Emerged? ... When did life appear on earth? .... Did the earth's primitive atmosphere contain molecular oxygen?

text: The

text: Origin

text: of

text: Life

text: How

text: Did

text: Life

text: on

text: Earth

text: Emerged

text: When

text: did

text: life

text: appear

text: on

text: earth

text: Did

text: the

text: earth

text: 's

text: primitive

text: atmosphere

text: contain

text: molecular

text: oxygen

title: /process.php?d=6dlblZPpqk0qyMysvIeHq%2FEQie3M0yPoQSkoqna4VoQqojgestGYQSVWaCp%2B2trXVCs%2FuEYsw4sUqqQ%3D&b=1

text: Apr 24, 2013 - The emergence of oxygen in the Earth's atmosphere and in its ... We thus have four issues that appear at variance with each other: 1) the ...

text: Apr

text: The

text: emergence

text: of

text: oxygen

text: in

text: the

text: Earth

text: 's

text: atmosphere

text: and

text: in

text: its

text: We

text: thus

text: have

text: four

text: issues

text: that

text: appear

text: at

text: variance

text: with

text: each

text: other

text: the

title: /process.php?d=6dlblZPpqkky1Ne8up3GpvAY0c%2FN6znqAER88iHICch8oTQUssOZVglHVjli0%2BDTFkNm4CBYjJEUr%2B%2FuCa6I0UuU2wWDfpGlzNZgSlw%3D&b=1

text: How did oxygen form in earth's early atmosphere? Stromatolites converted the toxic atmosphere into a breathable one. They appear in the fossil record starting ...

text: How

text: did

text: oxygen

text: form

text: in

text: earth

text: 's

text: early

text: atmosphere

text: Stromatolites

text: converted

text: the

text: toxic

text: atmosphere

text: into

text: a

text: breathable

text: one

text: They

text: appear

text: in

text: the

text: fossil

text: record

text: starting

title: /process.php?d=6dlbkYf34UY%2Fwo6zuo%2BGrrEajPnNzDDoC2g3qnavUZ9GrjQXhMaRSFd2fzd%2B1vHbC3Ih5gtwgQ%3D%3D&b=1

text: The oxygen in the atmosphere gave rise to the ozone layer which then shielded Earth from ultraviolet radiation. Newer versions ... "Did Life Have a Simple Start?

text: The

text: oxygen

text: in

text: the

text: atmosphere

text: gave

text: rise

text: to

text: the

text: ozone

text: layer

text: which

text: then

text: shielded

text: Earth

text: from

text: ultraviolet

text: radiation

text: Newer

text: versions

text: Did

text: Life

text: Have

text: a

text: Simple

text: Start

title: /process.php?d=6dlbjI3q9kdyxcm2u42B6%2F4Hl%2BSN0jChC39ttCb4E8J2oyJVqOCyFUoGJjR3wPHHFnl8oTBvhIQJqbvCOa22706L4UuYYZex1dB2FlFweSM%3D&b=1

text: Current atmosphere is oxygen rich (Oxidizing). Breaks down Organic molecules; One manifestation of this is fire. Early Earth' s atmosphere was slightly reducing.

text: Current

text: atmosphere

text: is

text: oxygen

text: rich

text: Oxidizing

text: Breaks

text: down

text: Organic

text: molecules

text: One

text: manifestation

text: of

text: this

text: is

text: fire

text: Early

text: Earth

text: s

text: atmosphere

text: was

text: slightly

text: reducing

title: /process.php?d=6dlblZPpql8z1cy95YydrPMRm%2ByRkj79CTR0%2FjbkCd526T0fntbfSB9APXd31u7TFmVg%2Bhpuw4sUqqQ%3D&b=1

text: There was iron dissolved in the water,as well, and for millions of years the iron combined with the oxygen and so did not escape into the atmosphere. Geologists ...

text: There

text: was

text: iron

text: dissolved

text: in

text: the

text: water

text: as

text: well

text: and

text: for

text: millions

text: of

text: years

text: the

text: iron

text: combined

text: with

text: the

text: oxygen

text: and

text: so

text: did

text: not

text: escape

text: into

text: the

text: atmosphere

text: Geologists

title: /process.php?d=6dlblZPpqlsxztSxu4GGrP4bk%2F%2BFkjLgAzRr%2BCzyCNNg6z8bmdCCQVVbZi8%2Fx%2BzWSWtu%2BhpvwIAPqq2wIqTExkaf8AzaJMzmj4k3DAEr&b=1

text: Oxygen and hydrogen commingle to make H2O. ... including epochs with high ambient temperatures and no enveloping atmosphere, implies that ... of different forms of hydrogen in asteroids appear to better match what we find here on Earth.

text: Oxygen

text: and

text: hydrogen

text: commingle

text: to

text: make

text: including

text: epochs

text: with

text: high

text: ambient

text: temperatures

text: and

text: no

text: enveloping

text: atmosphere

text: implies

text: that

text: of

text: different

text: forms

text: of

text: hydrogen

text: in

text: asteroids

text: appear

text: to

text: better

text: match

text: what

text: we

text: find

text: here

text: on

text: Earth

title: /process.php?d=6dlblZPpqk4wxtOxq4%2BaofIUnfaL0jShDXR1tDHyFcQo9GhNw82ESRY%3D&b=1

text: Mar 4, 2010 - The introduction of free oxygen into the atmosphere 1.8 billion years ago. pg. 185 ... When did life first appear on Earth? How do we know?

text: Mar

text: The

text: introduction

text: of

text: free

text: oxygen

text: into

text: the

text: atmosphere

text: billion

text: years

text: ago

text: pg

text: When

text: did

text: life

text: first

text: appear

text: on

text: Earth

text: How

text: do

text: we

text: know

question: when did oxygen appear in the atmosphere?

answer: 3.5 billion years ago

aliases:
2.7 billion years ago
3.5 billion years ago

text: 3.5 billion years ago

text: 3.5 billion years ago