If you wanted to consult the geologic period for when the first vertebrates evolved, where would you look?

Question

a. in the section for the Ordovician period of the Paleozoic era.
b. in the section for the Quaternary period of the Cenozoic era.
c. in the section for the Triassic period of the Mesozoic era.
d. in the section for Precambrian time.

After a rock layer is eroded, which additional event must occur to create an unconformity, or a gap in the geologic record?

a. an earthquake or motion along a fault.
b. new deposits of sediment must build up on the eroded area.
c. folding of sedimentary rock layers.
d. a volcanic eruption.

A and A

Answer 1

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