Earth’s Surface, Earth’s History and Maps

Bedrock and Soil The outer layer of the earth is the crust. Crust – made of bedrock, rock fragments and soil. Bedrock is solid rock Outcrops are where bedrock is exposed Soil consists of rock fragments and organic material

Minerals Rocks are made of two or more minerals. Tests Hardness Luster Cleavage Streak Color Acid

Rocks Igneous – form by cooling magma. The slower they cool the bigger the crystals are. Sedimentary – form by particles compacting and cementing Usually form underwater Only type that contain fossils Metamorphic – form by intense heat and pressure Never fully melt change igneous and sedimentary rocks.

Interpreting Rocks Sedimentary rocks contain fossils which help determine the environment of an area. Folds and faults make it difficult to determine the rock age but give clues to geologic events. Layer on the bottom is the oldest layer Scientists also use radioactive dating to determine the age of rocks.

Latitude and Longitude Longitude runs north and south Measured in degrees east and west from 0-180 Prime meridian is 00 International dateline is 1800 Latitude runs east and west Measured north and south from 0-90

Topographic Maps Topographic maps show contour lines with equal elevations. Contour interval is the change in elevation (height) from one line to the next) Closely spaced lines indicate a steep slope Widely spaced line indicate a gentle slope Circular lines make a hill