earth geologic history notes

Radioactive Decay

What is the process of breaking down? Answer with a single words or term.

North America

________ was over the equator and our climate was warm with few seasonal changes.

Geologists

________ determine absolute ages by using properties of the atoms that make up materials.

Trilobites

What are found throughout the Paleozoic era but never more abundant & widespread then the Cambrian (index fossil)

Fossil

A(n) ________ is any evidence of earlier life preserved in the rock.

Outcrop

What is exposed rock layers at the earths surface? Answer with a single words or term.

Radiocarbon Dating

________: Uses the Radioactive Isotope Carbon- 14 found in all living things.

Key bed

A(n) ________ is a thin, widespread layer, usually of volcanic ash that can be used to correlate an exact point of time.

Paleozoic era

The ________ marks the beginning of an abundant fossil record.

Radiometric Ages

________ are by measuring the ratio of parent isotope to daughter product in a mineral and by knowing the half- life of the parent, in many cases, you can calculate the absolute age of a rock.

Cambrian Period

________- Trilobites & Brachiopods are the most common fossil.

Index Fossil

________- short- lived, geographically widespread occurrence.

Absolute Age

________ is the age in years, of a rock or other object.

Radioactive Isotopes

________: Atoms of elements that give off radiation from their nuclei.

Radioactive Dating

________: Used to date back in time, certain rocks contain radioactive isotopes.

Precambrian time

________ is all of the geologic time before the Paleozoic Era, Precambrian rocks lack fossils because most of the organisms were microscopic bacteria and algae, Stromatolites are algal reefs that make up a large part of the fossils from the Precambrian, ½ Of the worlds metallic minerals are found in Precambrian rocks.

Relative time

________: Places events in a sequence but does not identify their actual date or occurrence (ex: a list in chronological order of what you have done today up until this time)

Half Life of an isotope

What is the time it takes for half of the atoms in the isotope to decay? Answer with a single words or term.

Radioactive Decay

________: The process by which a radioactive isotope changes into a new stable element.