lava that hardens on the surface and forms igneous rocks
What is extrusion?
100
Scientist propose that Earth is this old
What is 4.6 Billion years?
100
Elements release particles and energy in this process
What is radioactive decay?
200
fossils in which minerals replace all of an organism, or part of such as a dinosaur bone
What is petrified fossils?
200
A type of organism that no longer exists and will never again live on Earth
What is extinct?
200
magma cools and hardens into a mass of igneous rock subsurface.
What is intrusion?
200
The key principle that guides scientist when they make inferences about Earth's past is the principle of
What is uniformitarianism?
200
The time it takes for half of the radioactive atoms to decay
What is half-life?
300
extremely thin coating of carbon on rock
What is carbon films?
300
A rocks age compared to the ages of other rocks
What is relative age?
300
a break in Earth's curst
What is fault?
300
Trace Fossils always form in soft sediment. What describes two types of trace fossils?
What is molds and casts?
300
How Earth formed
What is rock, ice, and dust that were left over after the sun formed?
400
provides evidence of the activities of ancient organisms. Example: fossilized footprint
What is trace fossil?
400
the number of years that have passed since the rock formed
What is absolute age?
400
fossils that help geologist match rock layers. To be useful, a fossil must be widely distributed and represent an organism that existed for a geologically short period of time
What is index fossil?
400
Sedimentary rock forms in what type of layers?
What is horizontal?
400
This force pulled lumps of material together
What is gravity?
500
A scientist that studies fossils
What is paleontologist?
500
the law that scientists use to determine the relative age of sedimentary rock layers?
What is law of superposition?
500
When rock layers erode away, an older rock surface may be exposed. The surface where new rock layers meet a much older rock surface is called
What is unconformity?
500
A record of the geologic events and the evolution of life forms as shown in the fossil record