Fossils

10 cards·by elivingston

forms when a footprint or trail trapped in mud or sand hardens to stone

trace fossil

forms when leaves and stems are pressed between layers of soft mud or clay leaving a carbon imprint on rock

carbon film

forms when entire organisms or parts are prevented from decaying and are trapped in rock, ice, tar, or amber

preserved remains

forms when minerals soak into the remains, replace them, and changes them into rock

permineralized

forms when sediments bury an organism, decays leaving a cavity in the shape of the organism

mold

forms when a mold is filled with sand or mud and hardens into the shape of the organism

cast

used by geologists to date rock layers

index fossils

the age of something compared with other things

relative age

top rock layers are younger and get older as you go down

law of superposition

remains of prehistoric organisms that can tell when, where, and how organisms once lived

fossils