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- Why are so few Precambrian rocks exposed on Earth's surface?
- Why are fossils rarely found in Precambrian rock?
- Where can we find Precambrian rocks?
- What are Precambrian rocks?
- Why do geologists know so little about Precambrian history?
- What does Proterozoic mean is this accurate explain?
- What happened when temperatures decreased during the ice ages of the Cenozoic Era?
- How were stromatolites formed?
- When a scientist discovers a new type of fossil What characteristics of the rock around the fossil would he or she want to learn first?
- How do scientist determine the age of rocks?
- Where is the oldest rock in the world found?
- Which is the oldest rock in India?
- Why is the Precambrian era important?
- What caused the Precambrian era to end?
Why are so few Precambrian rocks exposed on Earth's surface?
Due to the fact that fossils from the Precambrian Period are limited, very few fossils can be found in Precambrian-aged rocks and these mostly of single celled organisms that don't change much over long periods of times.
Why are fossils rarely found in Precambrian rock?
Fossils are rare in Precambrian rocks, probably because Precambrian life-forms lacked bones, shells, or other hard parts that commonly form fossils. ... Of the few Precambrian fossils that have been discovered, the most common are cyanobacteria in stromatolites, or layered, reef- like deposits.
Where can we find Precambrian rocks?
The distribution of Precambrian rocks is worldwide, but in the United States rocks of this age are found in the cores of major mountain ranges. They also occur in the Lake Superior region and in a few localities in the southwest.
What are Precambrian rocks?
Collectively, Precambrian rocks of Minnesota encompass metamorphic, igneous, and sedimentary rocks. Examples include gneiss, greenstone, granite, graywacke, iron-formation, schist, basalt, gabbro, and anorthosite.
Why do geologists know so little about Precambrian history?
why do geologists know so little about precambrian history? it covers an enormous time period and precambrian rocks are often severely deformed. ... You need to know a lot about geology because fossils are found in layers of rock (strata) and you can figure out how old they are from what layer they are in.
What does Proterozoic mean is this accurate explain?
The Proterozoic is a geological eon representing the time just before the proliferation of complex life on Earth. The name Proterozoic comes from Greek and means "earlier life".
What happened when temperatures decreased during the ice ages of the Cenozoic Era?
During the Cenozoic Era, dramatic changes in climate have occurred. As temperatures decreased during the ice ages, new species that were adapted to life in cooler climates appeared. Mammals became the dominant life-form and underwent many changes.
How were stromatolites formed?
Stromatolites – Greek for 'layered rock' – are microbial reefs created by cyanobacteria (formerly known as blue-green algae). ... Stromatolite deposits are formed by sediment trapping and binding, and/or by precipitation activities of the microbial communities (Awramik 1976).
When a scientist discovers a new type of fossil What characteristics of the rock around the fossil would he or she want to learn first?
(see Figure 1 on page 211 for example ). 7 #4 When a scientist discovers a new type of fossil, what characteristics of the rock around the fossil would he or she want to learn first? The first thing a geologist would want to learn is the age of the rock in which the fossil was found.
How do scientist determine the age of rocks?
The age of rocks is determined by radiometric dating, which looks at the proportion of two different isotopes in a sample. Radioactive isotopes break down in a predictable amount of time, enabling geologists to determine the age of a sample using equipment like this thermal ionization mass spectrometer.
Where is the oldest rock in the world found?
Bedrock along the northeast coast of Hudson Bay, Canada, has the oldest rock on Earth. Canadian bedrock more than 4 billion years old may be the oldest known section of the Earth's early crust.
Which is the oldest rock in India?
The zircon containing granite rocks of Odisha. About 4.24 billion years old – older than the oldest rocks on Earth – and barely the width of a human hair, tiny grains of zircon have been found trapped in a granite rock in the eastern Indian state of Odisha1.
Why is the Precambrian era important?
The Precambrian is the earliest of the geologic ages, which are marked by different layers of sedimentary rock. Laid down over millions of years, these rock layers contain a permanent record of the Earth's past, including the fossilized remains of plants and animals buried when the sediments were formed.
What caused the Precambrian era to end?
During the late Precambrian, continents drifted, carbon dioxide levels fluctuated, and climates changed. Many organisms could not survive the changes and died out. ... The Precambrian ended with a mass extinction, which paved the way for the Cambrian explosion.
