Exam 23: Geologic Timereading the Rock Record

In a sequence of rock layers we find trilobite fossils at the bottom of the rock sequence and dinosaur fossils directly above the trilobite fossils. We conclude that

The time required for one-half of a radioactive material to decay is called the

Relative dating tells us the

Radiocarbon dating is limited to the remains of plants and animals that died no longer than about

The oldest known fossils are

The numerical dates associated with events on the geologic time scale were determined by

Development of Earth's early oceans was likely due to

Possible ways that sea level could lower include a decrease in

The Cenozoic Era is known as the

What are some of the uncertainties in obtaining radiometric carbon dates?

In a sequence of rock layers we find trilobite and dinosaur fossils. The dinosaur fossils are at the bottom of the rock sequence and the trilobites are at the top. This sequence tells us that

The formation of the supercontinent of Pangaea caused

A surface of erosion between rocks that represents a gap in Earth history is

Radiometric dating assumes that, once a mineral has crystallized, any daughter product results only from the decay of the original unstable parent. Some complications are

Why does sea level rise when spreading rate increases?

Why are periods the most fundamental time unit?

In a sequence of sedimentary rocks, the bottom layer is the youngest and the top layer is the oldest. This type of sequence suggests that the

Ancient geologic processes as revealed in Paleozoic rock layers were

When tilted or folded sedimentary layers are covered by younger, horizontal rock layers it is called

The breakup of Pangaea resulted in the separation of