Approximately how long ago did free oxygen first appear in Earth's atmosphere?
A. 1 billion years ago
B. 2 billion years ago
C. 3 billion years ago
D. 4 billion years ago
Answer: B
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Other than composite volcanoes, what volcanic landform can generate a pyroclastic flow?
What will be an ideal response?
Fault-block mountains are created due to ________ faults
A) reverse B) strike-slip C) thrust D) normal
Sediments derived from preexisting rocks on land are called ________
A) cosmogenous B) biogenous C) hydrogenous D) lithogenous E) volcanogenic
Characteristic fauna of what biome include large ungulates (hooved mammals), such as giraffe, zebra, buffalo, gazelle, wildebeest, antelope, and rhinoceros?
A) Boreal and montane forest B) midlatitude broadleaf and mixed forest C) midlatitude grassland D) tropical rain forest E) tropical savanna