Ees 1030 1st Edition Lecture 8Current LectureGeological time: record of earth’s history divided into units. Ways to date geological events:Relative dating: determines whether a rock isolder or younger than surrounding rocks. Canbe done by observations.Absolute dating: determining the exact number of years since the formation of a rock. Radiocarbon dating. Nicolaus Steno: says “in an undeformed sequence of layered rocks, the younger rocksare on the top.” If rock layers are flat then they have not been disturbed. Cross cutting: this says that the geological feature that is “cutting” into another feature is the younger of the 2 features. Inclusions: a piece of rock that is enclose within another piece of rock. The inclusion will always be older than the host rockUnconformities:- Angular unconformities: an older section of sediments has been tilted by erosion, and newer sediments are deposited on top- Disconformities: erosion between 2 sections of sediment. Strata on either side of the unconformity are parallel- Nonconformities: metamorphic or igneous rocks come in contact with sedimentary strata.Correltion: when matching rocks of similar ages are in different reagions.- Correlation relies on biostratigraphy (fossils)- Fossils: traces or remains of prehistoric life that is preserved in sedimentary rocks. Rocks can also be dated by using overlapping fossil ranges.Fossils also can be used to recognize a break in the sedimentary record.The geological time scale is a calendar of earth’s history and is divided into units using relative
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