ASBOG Paleontology and Geochronology

Question 1

Which radiometric dating method relies on the decay of uranium-238 to lead-206?

Accepted Answer

Uranium-Lead dating

Answer

Uranium-Lead (U-Pb) dating uses the decay of ²³⁸U to ²⁰⁶Pb (half-life ~4.47 billion years), making it suitable for dating very old rocks and zircon minerals.

Question 2

The Cambrian Explosion is significant in paleontology because it marks:

Accepted Answer

The rapid diversification of complex multicellular animal body plans

Answer

The Cambrian Explosion (~541 Ma) records the geologically rapid appearance of most major animal phyla, with diverse hard-shelled organisms appearing in the fossil record for the first time.

Question 3

Which group of fossils serves as the best index fossils for Cretaceous marine sediments?

Accepted Answer

Ammonites

Answer

Ammonites were abundant, rapidly evolving, and widespread in Mesozoic seas, making them excellent index fossils for correlating Cretaceous marine strata globally.

Question 4

The half-life of Carbon-14 (¹⁴C) used in radiocarbon dating is approximately:

Accepted Answer

5,730 years

Answer

¹⁴C has a half-life of ~5,730 years, limiting its effective dating range to materials younger than ~50,000 years before atmospheric ¹⁴C becomes undetectable.

Question 5

Which geologic era spans from approximately 252 to 66 million years ago?

Accepted Answer

Mesozoic Era

Answer

The Mesozoic Era (252–66 Ma) is bounded by the Permian-Triassic extinction at its base and the Cretaceous-Paleogene extinction at its top, and encompasses the Triassic, Jurassic, and Cretaceous periods.

ASBOG - Association of State Boards of Geology Practice Test

ASBOG - Association of State Boards of Geology Practice Test

ASBOG Paleontology and Geochronology