Ch 5

Ch. 5 Note: not covered –names of types of rock units, correlation
Concepts: unconformities – disconformity, angular unconformity, nonconformity
sedimentary facies
marine transgression – regression – Walther’s law
Review terms: angular unconformity, conformable, disconformity, fossil (in general),
marine regression, marine transgression, nonconformity, principle of fossil
succession, principle of inclusions, relative geologic time scale, sedimentary facies,
unconformity, Walther’s law
Fossil preservation: environments favorable: rapid burial, mud, submarine fan
(landslide), lake bottom; ice, amber (tree sap), tar, mummification
body types: exoskeletons (i.e. clam), large bones
Types: body fossils, trace fossils, molds, casts
body fossils, whole body fossils, altered remains, unaltered remains
(original material preserved)
Table 5.1: alteration types: carbonization, replacement (pyrite
on a shell), permineralization (petrified wood)
Marine transgressions: sea level rise. Facies migrate landward: offshore facies
(limestone) moves over nearshore. nearshore facies (shale) moves over shoreline;
shoreline facies (sandstone) is beneath the shale and limestone. Walther’s law: the
facies observed in a conformable (undisturbed) vertical sequence will replace one
another laterally.
Marine regression: sea level drop. Facies migrate seaward: shoreline facies (sandstone)
moves over nearshore (shale); nearshore facies moves over offshore facies (limestone).
Causes of changes in sea level: climate change (melting or freezing of Earth’s surface
waters); underwater volcanism (increase or decrease in the rate of sea floor
spreading); uplift or subsidence of continents