fossils Flashcards
(68 cards)
a body of sediment with distinctive physical, chemical, and biological attributes
sedimentary facies
sea level rose with respect to the land
marine transgression
when sea level fell with respect to the continent and the environments that paralleled the shoreline migrated seaward
marine regression
another aspect of this is that the rocks making up each facies become younger in landward direction
marine transgression
this holds that the facies seen in a conformable vertical sequence will also replace one another laterally
walther’s law
he recognized that the facies seen in a conformable vertical
sequence will also replace one another
laterally, year of birth and death?
johannes walther, 1860-1937
true or false, walther’s law can be applied to rocks above and below an unconformity
false, unconformities are unrelated and law does not apply
what are the 3 causes of marine transgression and regression
uplift and subsidence
amount of water frozen in glaciers
rates of seafloor spreading
it is the scientific study of fossils
paleontology
5 favorable conditions for fossilization
- possession of hard parts like exoskeleton, bones, nails, and tooth
- rapid burial
- availability of finer sediments and undisturbed conditions of sedimentation
- presence of highly mineralized groundwater
- calm water, little oxygen (anoxic environments)
these are the remains or traces of prehistoric organisms preserved in rocks
fossils
which rocks are these remains or traces are commonly found
sedimentary rocks
3 uses of fossils
- determine the relative ages of strata
- for determining environments of
deposition - constitute some of the evidence for the
theory of evolution
type of fossil that are the skeletal parts, shells, bones and teeth
body fossils
type of fossil that indicates organic activity such as tracks, trails, burrows, nests, and feces or coprolites
trace fossils
original composition and preserved structures of body fossils
unaltered remains
bones, insects preserved in asphalt-like substance at oil seeps
preservation in tar
one chemical replaces another, e.g. pyrite replaces calcium carbonate of shells
replacement
large ice age mammals frozen in sediment
freezing
a cavity with the shape of a bone or shell
mold
this happens when a cavity with a shape of a bone or shells gets filled by minerals or sediments
casts
change in crystal structure, e.g. aragonite in shells recrystallizes as calcite
recrystallization
air drying and shriveling of soft tissues
mummification
leaves, insects, and small reptiles trapped and preserved in hardened tree resin
preservation in amber