Contact metamorphism: occurs at the border where magma touches solid rock- at this boundary, the rock is turned into metamorphic rock through contact with the heat of the magma. Use the ESRT to determine the type of sedimentary rock, then the metamorphic rock table to determine what the sedimentary rock turns in to at this contact boundary
1Approximately how many million years ago did the earliest amphibians appear?362-418 2Approximately how many million years ago was the initial opening of the Atlantic Ocean? 142-206 3During which era did the earliest fish appear?Paleozoic 4During which epoch did large carnivores appear?Pliocene 5Of the following rocks which would be most likely to contain fossils? a. rhyoliteb. basaltc. metaconglomerated. limestone limestone (its sedimentary) 6At Binghamton, NY what is age of the bedrock?Devonian (362-418 million years) 7How does the age of the bedrock at Old Forge compare with that at Jamestown?Jamestown is younger 8Name a location in NY State where you may be able to find bedrock which was formed at the peak of the eurypterids development. Silurian age bedrock: Niagara Falls, Syracuse 9Why would fossils be unlikely to be found in quartzite?its metamorphic 10For each of the following locations in NY State below, identify whether fossils would be likely or unlikely: Old Forge; Binghamton; Albany Old Forge: unlikely Binghamton: likely Albany: likely
Half-Life A half-life is the amount of time necessary for one-half of a radioactive, unstable substance to become not radioactive, stable. Half life depends on the element that is unstable- some radioactive isotopes stabilize quickly, some take much longer
Radioactive IsotopeCircumstance to Use Carbon-14Anything organic or of relatively recent origin- Use if a fossil of any kind is mentioned in a question! PotassiumFor rocks more than 70,000 years in age Uranium-238Relatively middle-aged rocks Rubidium-87A rock of ancient origin
Dating with Carbon-14 When an organism dies, the amount of carbon-14 it contains decreases at a predictable rate By comparing the ratio of carbon-14 to Nitrogen-14 in a sample, absolute age can be determined.
What can be done to change the half-life of a radioactive isotope? Why is this important? NOTHING! it is reliable to calculate age
If there is a 100g sample of C 14, how many grams of C 14 would remain after three half-lives? How long would this take? Show all work. 100g50g25g12.5g 3 half-lives x (5.7 x 10 3 ) =1.71 x 10 4 = 17,100 years