Geologic Time Scale Ch 18

Geologic Time Scale Law of superposition- youngest is on top oldest on bottom Geologic column- arrangement of rock layers

Era- A very large unit of time Period-A division of an Era Epoch-A division of a Period

Section 18.1 review Scientists use events such as major changes in the earth’s surface and climate and the extinction of various species as the basis for dividing the geologic time scale into units. True

True False Section 18.1 review Using the law of superposition and the study of index fossils, nineteenth century scientists determined the relative ages of rock layers True False Eras are subdivisions of periods

False True Section 18.1 review Scientists can use the geologic column to estimate the relative ages of rock layers only if the rock contains radioactive minerals False Fossils of mammals are common in Cenozoic rocks True

Complete the statement Rock layers in the geologic column can be distinguished from one another according to rock type and__________ The geologic era that followed Precabrian time is called the _________ Fossil content Paleozoic Era

Complete the statement According to the geologic column in the diagram, the oldest rock layer is__________ Based on late Precambrian fossils and other types of geological evidence, scientists theorize that life began _________ Layer 4 In the ocean

Last question in 18.1 The era that is divided into epochs is the ___________ Cenozoic Era

Theory of Evolution Organisms change over time. New kinds of organisms are derived from ancestors.

Precambrian time Started 4.6billion years ago Ended 540million years ago Characteristics of this time: Soft-bodies or single cell organisms, Stromatolites Lots of volcanoes, mountain formation, sediment formation & metamorphism

Paleozoic Era 540-248 million years ago Periods: Cambrian Ordovician Silurian Devonian Carboniferous Permian

Paleozoic Era 540-248 million years ago Cambrian Advanced forms of marine life and first invertebrates appear Ordovician Brachiopods increase: trilobites decline: graptolites flourish: First vertebrates (fishes appear)

Paleozoic Era 540-248 million years ago Silurian First land plants and animals appear Devonian Age of fishes First amphibians Ferns and cone bearing plants

Paleozoic Era 540-248 million years ago Carboniferous Split into two epochs: Mississippian and Pennsylvanian Amphibians flourish Giant cockroaches Permian Pangaea comes together mass extinctions

Mesozoic Era 248-65 million years ago Periods Triassic First Dinosaurs, tropical weather, Jurassic Large Dinosaurs, tropical weather, Cretaceous First flowering plants, mass extinction

Cenozoic Era 65 million years to today Periods Tertiary Paleocene Oilgocene Miocene Pliocene Quaternary Pleistocene Holocene

Cenozoic Era 65 million years to today Periods Tertiary Age of mammals Pangaea separates Quaternary Ice age and human’s develop

18.2 review The presence of cross-bedded sandstone may indicate that the region where it is present was once: Shields are large areas of exposed rock of what era? The fossil record indicates that which of the following thrived during the Paleozoic Era A desert Precambrian Advanced forms of marine life

18.2 review The Devonian period is also known as the Age of Dinosaurs first appeared during the During which era did glaciers cover nearly one third of the earth’s land area? Fishes Triassic period Cenozic

Cambrian Ordovician_________Devonian 18.2 review During which epoch did the first modern horses appear? Which geologic period is missing from this diagram? Pilocene Silurian The Paleozoic Era Cambrian Ordovician_________Devonian  Time

18.2 review What are the most common Precambrian fossils called? Which period of the Cenozoic Era includes the time before the last major ice age Stromatolites Tertiary