fossil records

Question 1

uniformitarianism

Answer 1

the theory that changes in the earth’s crust during geological history have resulted from the action of continuous and uniform processes.

Question 2

catastrophism

Answer 2

the theory that changes in the earth’s crust during geological history have resulted chiefly from sudden violent and unusual events.

Question 3

Paleontology

Answer 3

Paleontology is the scientific study of life in the geologic past, based on examination of fossilized remains of once living organisms, such as tracks, bones, teeth, plants, and shells. Fossils are unique, nonrenewable resources that paint a ancient portrait of life on Earth.

Question 4

relative dating

Answer 4

Relative dating is the process of determining if one rock or geologic event is older or younger than another, without knowing their specific ages—i.e., how many years ago the object was formed.

Question 5

absolute dating

Answer 5

Absolute dating methods measure the physical properties of an object itself and use these measurements to calculate its age. One of the most useful absolute dating methods for archaeologists is called radiocarbon dating.

Question 6

superposition

Answer 6

Superposition is the ability of a quantum system to be in multiple states at the same time until it is measured. Because the concept is difficult to understand, this essential principle of quantum mechanics is often illustrated by an experiment carried out in 1801 by the English physicist, Thomas Young.

Question 7

Isotope

Answer 7

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

Question 8

Radioactive decay

Answer 8

Radioactive decay is the process in which a radioactive atom spontaneously gives off radiation in the form of energy or particles to reach a more stable state. It is important to distinguish between radioactive material and the radiation it gives off.

Question 9

half-life

Answer 9

the time taken for the radioactivity of a specified isotope to fall to half its original value.

Question 10

fos·sil

Answer 10

the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.

Question 11

trace fos·sil

Answer 11

a fossil of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself.

Question 12

mold

Answer 12

Sometimes when an animal dies and its body decays, it can leave an imprint in the sediment. If this imprint fills in with minerals from sediment and groundwater, it can harden to form a fossil. This fossil is called a cast fossil. The fossilized imprint is called a mold fossil.

Question 13

cast

Answer 13

Sometimes when an animal dies and its body decays, it can leave an imprint in the sediment. If this imprint fills in with minerals from sediment and groundwater, it can harden to form a fossil. This fossil is called a cast fossil.

Question 14

unconformity

Answer 14

a surface of contact between two groups of unconformable strata.

Question 15

mass extinction

Answer 15

A mass extinction event is when species vanish much faster than they are replaced. This is usually defined as about 75% of the world’s species being lost in a ‘short’ amount of geological time - less than 2.8 million years.

Question 16

jurrasic period

Answer 16

The Jurassic period (199.6 million to 145.5 million years ago) was characterized by a warm, wet climate that gave rise to lush vegetation and abundant life. Many new dinosaurs emerged—in great numbers. Among them were stegosaurs, brachiosaurs, allosaurs, and many others. Artwork by Publiphoto/Photo Researchers Inc.

Question 17

cretaceous period

Answer 17

The Cretaceous is defined as the period between 145.5 and 65.5 million years ago,* the last period of the Mesozoic Era, following the Jurassic and ending with the extinction of the dinosaurs (except birds).

Question 18

devonian period

Answer 18

The Devonian is a geologic period and system of the Paleozoic, spanning 60.3 million years from the end of the Silurian, 419.2 million years ago (Mya), …

Question 19

quaternary period

Answer 19

The Quaternary Period is the third and last of the three periods of the Cenozoic Era. You and I are living in this period, which began only 2.58 million years ago. This is less than 0.1% of all of geologic time! A thin layer of sediments deposited during the Quaternary covers much of the Earth’s land surface.Jan 4, 2021

Question 20

permian period

Answer 20

Permian Period, in geologic time, the last period of the Paleozoic Era. The Permian Period began 298.9 million years ago and ended 252.2 million years ago, …