BIOEE 1780 Chapter Notes - Chapter 3: Arthropod, Burgess Shale, Calcite
31 Oct 2016
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Document Summary
Darwin was a geologist first and assumed that the earth must be billions of years old in order to be able to form geological formations such as ridges and valleys. Kelvin hypothesized that the earth"s age is determined by the current temperature of rocks. Fossils are remains or traces of once living organisms. Ordinary conditions impede fossilization: scavengers, bacterial decay, dissolution in water, physical disturbance (wave action, wind) Special conditions promote fossilization: rapid burial, burial is associated with anaerobic environments (if there"s no oxygen, then decay is limited, protection from physical disturbance (quiet, deep water) Burial is key: most fossils are found in sedimentary rocks: age of sediments give us date and time or preservation. Favorable environments: oceans collect the bulk of sediments, waterfalls open up sedimentary cores: bottom waters/sediments of deep, stratified lakes (water doesn"t turn over) are anoxic and below physical disturbance (waves) Less favorable enviornments: upland environments, continental deposits (sandbars & gravel pits)
