Exam 10: Deep Time: How Old Is Old

In an unweathered sample of igneous rock,the ratio of an unstable isotope to its stable daughter isotope is 1:15.If no daughters were present at the time the rock cooled below closure temperature,and the half-life of the isotope is 50 million years,how old is the rock?

A layer of shale that contains a distinctive fossil could be used as a ________.

Based on the figure,what is the age of layer 7 relative to layer 3?

Which image below shows a nonconformity?

Several geologic principles are used to determine ________ ages.

Concerning the relative ages of the granite and sandstone,________.

The correlation of data from geologic ________ and ________ helped geologists unravel the entire history of Earth.

Stratigraphic correlation is conducted by matching ________ and ________.

The surfaces named contacts #2 and #3 in the image below are examples of ________.

Which of the following is always the same for different isotopes of a single element?

Describe the plausible geologic history of the rocks in the diagram below.

The closure temperature represents the point when ________.

A ________ is a geologic layer that is distinct enough to allow it to be found regionally and used to correlate rocks.

If the relative ages of two formations are known,what else about them can be inferred?

Two layers of rock contain trilobites that have the same body morphology;however,one rock layer is a shale and the other is an ironstone.Can these two layers be used for correlation?