These These rocks are evidence that there was very little and isolated amounts o

Question

These These rocks are evidence that there was very little and isolated amounts of iron deposited with chert during the Precambrian These rocks are evidence that Earth's early atmosphere the same during the Precaibrian These rocks are evidence that oxygen must have been present ined oxygen was not yet present during during the Precambrian. The oxygen the Precambrian. was released as a by-product of photosynthesis. These rocks are evidence that significant amounts of iron were These rocks are evidence that oxygen and iron became iron oxide during the Precambrian released on the ocean ftoor bilions photosynthetic bacteria existed 35 billion years ago of years ago. True False

Explanation / Answer

True:

1.The rocks are evidences that photosynthetic bacteria existed 3.5M years ago.Well-preserved microscopic fossils of bacteria older than 3.46(~3.5)billion years have been found in Western Australia.

2. The rocks are evidence that oxygen must have been preserved during the Precambrian. The oxygen was released as a by product of photosynthesis.

3. These rocks are evidence that iron became iron oxide during the Precambrian.At first, oxygen would have quickly combined with other elements in Earth's crust, primarily iron, removing it from the atmosphere.

4. These rocks are evidence that very little amount of iron deposited with chert during Precambrian. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, and the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formationsthat were laid down as iron oxides.

5. The rocks are evidence that significant amount of iron were released at the ocean floor. A new study shows that iron-bearing rocks that formed at the ocean floor 3.2 billion years ago carry unmistakable evidence of oxygen.

False:

1. These rocks are evidence that earth's early atmosphere remained the same during the Precambrian.After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, and the modern high-oxygen atmosphere would have developed.

2. These rocks are evidence that oxygen was not yet present in the atmosphere during the Precambrian. There is evidence that an oxygen-rich atmosphere existed since the early Archean.

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