Geologic History Vocabulary Test Chapter 13 & 14

remains, imprints, or traces of once-living organisms #1 remains, imprints, or traces of once-living organisms

fossils of species that existed for short periods and were widespread #2 fossils of species that existed for short periods and were widespread

cavity in rock made when an organism decayed #3 cavity in rock made when an organism decayed

#4 method by which order of events or age of rocks is determined by examining the position of rocks in a layer

#5 formed when original materials in skeletal remains are replaced by minerals

#6 states that in a sequence of undisturbed rocks, the oldest rocks are on the bottom and the rocks become progressively younger toward the top

produced when sediments fill in a cavity made when an object decayed #7 produced when sediments fill in a cavity made when an object decayed

#8 process that uses the properties of atoms in rocks and other objects to determine their ages

fossil of thin layer of carbon atoms and molecules #9 fossil of thin layer of carbon atoms and molecules

#10 gaps in rock record made when agents of erosion remove existing rock layers

time it takes for half of an isotope's atoms to decay #11 time it takes for half of an isotope's atoms to decay

#12 method by which a geologist can calculate the absolute age of the rock by knowing the half-life of an isotope

#13 principle that earth's processes occurring today are similar to those that occurred in the past

#14 process that occurs when the number of protons in an atom is changed and a new element is formed

#15 one of four major subdivisions of geologic time-the longest subdivision (based upon the abundance of certain fossils)

division of Earth's history into smaller units #16 division of Earth's history into smaller units

#17 one of four major subdivisions of geologic time-characterized by the types of life existing worldwide at the time

#18 one of four major subdivisions of geologic time-second longest subdivision (marked by major, striking, worldwide changes in the types of fossils present

#19 one of four major subdivisions of geologic time-characterized by differences in life-forms which can vary from continent to continent

#20 used to study the passage of geologic time because of changes in their physical features through time

#21 a group of organisms that normally reproduces only with other members of their group

#22 blue-green algae thought to be one of the earliest forms of life on Earth

giant landmass or supercontinent meaning "all land" #23 giant landmass or supercontinent meaning "all land"

#24 longest part of Earth's history-includes the Hadean, Archean, and Proterozoic Eons (4.5 billion yrs. ago to about 544 million yrs. ago)

#25 (era of middle life) time of many changes on Earth (Pangaea)-from 248 million years ago to 65 million years ago

#26 (era of recent life) began about 65 million years ago and continues today

#27 (era of ancient life) began about 544 million years ago and ended about 248 million years ago