1.4 The Rock Cycle and the geologic time scale
minerals
minerals: naturally occurring substances made from elements.
inorganic
fixed chemical structre. ex: quartz and gold
rocks
composed of many different compounds, structure is not consistent
types of rocks
igneous
metamorphic
sedimentary
caused by volcanic eruptions after magma cools off
formed by massive heat or pressure. found by the fault lines
formed from sediment combining. small pieces from a river
geologic time scale
rock transformations
uplift, weathering, erosion, deposition, sedimentation, cementation
heat and pressure
melting and cooling
changes in atmosphere, geologic activity, evolution and extinction of plant and animal life
collected in layers upon layers of deposited over the course of 4.6 billion years
4 eras in the geologic time scale
ceozoic era
mesozoic era
paleozoic era
Precambrian era
cooler and drier climate, dominated by mammals. several ice ages. started 66mya
warm and wet. dominated by dinosaurs, ended when they went extinct
plants and animals began to inhabit the earth. began with cambrian explsion. ended with mass extinction
1st and longest era. earth's formation