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Bodies of rocks that are thick enough to be mappable with distinct upper and lower boundaries are officially designated as:

A guide fossil has some or all of the following desirable characteristics except:

The landward migration of a shoreline is known as a ______. 

The most accurate radiometric dates are obtained from radioactive isotopes in:

Select the item below that makes a good key bed for correlating a precise event in time:

A fossil’s “range” determines:

To determine the radiometric age of a rock, what must scientists be able to measure very accurately?

Radioactive parent Na 24 decays with a half-life of 15 hours.  Starting with 100 atoms of this isotopic parent, how many parent isotopes would remain after 45 hours?

The _____________ rotates around the ______________ during forearm pronation and supination

The bicep is an elbow flexor, shoulder flexor, and radio-ulnar supinator