Geo- Lab
Terms
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- 5 geologic principles
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1. Original Horizontality
2. Stratigraphic superposition
3. Unconformities
4. Cross-cutting
5. Inclusions - disconformity
- unconformity between parallel starta or lave flows. most are very irregular surfaces, and piences of the underlying rock are often included in the strata above them.
- angular unconformity
- unconformity between nonparallel strata
- nonconformity
- unconformity gormed when stratified sedimentary rocks are deposited on eroded igneous or metamorphic rock
- Unconformity
- rock surface that represents a gap in the geologic record
- Conformities
- rocks on both sides of these planar features fomred in a continual sequence
- Modes of preservation
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1.preservation without alteration (frozen, mummified, entrapment- liquid)
2.preservation with alteration (prevalent mode of preservation: permineralization, replacement, carbonization, recrystallization)
3.Casts and Molds
4.Trace fossils - Premineralization
- ie- petrified wood- water and chemicals can go through
- Carbonization
- occur when plant debris or soft-bodies animals die and are buried. remains are decompressed and the volatile constituents are released, leaving a thin carbon silhouette behind.
- Recrystallization
- occures to creat a fossil when the substances that comprise the original organism (shell and bone) are converted to a more stable substance. ie- conversion of aragonite, a less stable form of calciium carbonate into calcite, a more stable from which occurs in same shell fish
- Biodiversity
- examination of the fossil record indicates that as organisms evolved the number of species increased.
- Phyletic gradualism
- hypothesis involving gradual changes in organisms over a long period of time and involving numerous generations
- Punctuated equilibrium
- no chnage occurs for extended periods and then, due to some sudden environmental change, a species must evolve rapidly to adjust to the new conditions
- fossil assemblage
- group of preserved organisms that cohabited a specific place at the same time
- geologic map
- topographic map with added info about the location and orientation of rock units and structures present in the area.
- cross section
- topographic profile with added info about the rock units and structures, depicted with the smae colores and symbols used in the geologic map
- quaternary map
- graphic representation of the distribution and identity of unconsolidated sediments which were deposited during the quaternary period
- surficial map
- combination of both the geologic and quaternary maps and shows the surface material whether it is bedrock or sediment
- stratigraphy
- study of the rock layers within the earth