OBJECTIVE LIFE SCIENCE
EVOLUTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Earth’s crust has frequently shifted.
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It has had extensive climate change.
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An ocean covered the area in the past.
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Sediments have only begun forming recently.
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Detailed explanation-1: -Which factor is a challenge to geologists in establishing the boundaries of the geologic time scale? Most rocks do not contain minerals that can be dated using radiometric dating.
Detailed explanation-2: -Evidence of Earth’s Past Scientists use the geological time scale to describe Earth’s history from its formation to the present day. The time span of 4.5 billion years is divided into smaller segments or units called eons, eras, periods, epochs, and ages (Table 7.2).
Detailed explanation-3: -Geologic Dating Scientists can learn about the history of the Earth by studying rocks and fossils. Rocks provide clues about what was happening on Earth when they formed. Geologists study rocks in order to figure out the Earth’s history. A very important part of this process is figuring out the age of different rocks.
Detailed explanation-4: -Fossils document the existence of now-extinct species, showing that different organisms have lived on Earth during different periods of the planet’s history. They can also help scientists reconstruct the evolutionary histories of present-day species.