Log in Sign up. How can we help? What is your email? Upgrade to remove ads. What is a fossil? How did early scientists believe fossils formed? What events were considered catastrophic disasters? Why was catastrophism abandoned? Because Earth's history is full of violent events. How old did scientists who supported catastrophism think that the Earth was? Who was James Hutton? A naturalist and farmer who thought that the processes that shaped whatt farm could also shape the earth.
Why dating in vernon texas James Hutton think racioactive the earth was much older than those who believed in catastrophism? Because erosion would take a long time to change the earth. How does uniformitarianism think that the earth surface changes? It is constantly being reshaped in a steady, uniform manner. What is the basis for understanding the Earth's past?
What happens to most organisms when they die? They decay and leave no trace that they ever lived. What increases the probability of an organism becoming a fossil? If it has hard parts such as shells, teeth, or bones and if it is buried quickly after it dies. Fossils that you need to use a microscope to see. What are the ways that fossils can be preserved?
What are preserved remains? When the actual remains of an organism is preserved as a fossil. What has to happen to make a preserved remain? The organism needs to be completely enclosed in some material over a long period of time. How old are preserved remains usually? What is a carbon film? When do carbon films form? When exposure to heat or pressure forces the gas and liquids out of an organism's tissue. How does mineral replacement form a fossil?
Minerals in groundwater fill in the pore spaces or replace the tissues of an scidntists. What is a mold? An impression in a rock left by an ancient organism. How does a mold form? Sediment hardens around a buried determinee and when the organism decays, an impression is left. What is a cast? A fossil copy of an organism made when a mold of the organism is filled with sediment or mineral deposits.
What is a trace fossil? What is a paleontologist? A scientist who studies fossils. What can paleontologist learn from applying uniformitarianism to the study of fossils? They learn about ancient organisms and the environments where they lived. Given an example of how paleontologists can apply uniformitarianism to studying fossils.
United States was once covered by what? What did scientist find there? A shallow sea, million years ago. Fossils allowed scientists to learn about that sea. What have fossils shown about ancient climates? What type of fossils are very good at showing climate change? What was the climate like when the dinosaurs lived? Cold, with huge sheets of ice and tall grasses on land. What is relative age? How do geologists organize the layers of rocks in a geologic formation? By the age of the rock layers.
The principle that in undisturbed rock layers, the oldest rocks are on the bottom. What is original horizontality? Most rock forming materials are deposited in horizontal layers. What is lateral continuity? Layers are deposited in continuous sheets in all directions until they thin out or hit a barrier. If rock layers are what does radioactive dating allow scientists determine or folded, does the principle of what does radioactive dating allow scientists determine horizontality still apply?
Yes, because the layers were still deposited horizontally, even if they are no longer horizontal. If a river erodes layers, speed dating 2 jogo the principle of lateral continuity still apply? Yes, because the placement and order of the layers does not change. What is an inclusion? A piece of an older rock that becomes part of a new rock. How do inclusions form? When part of an existing rock breaks off and falls into sediment or magma which then become rock.
What is the principle of inclusions? What is a vertical intrusion called? What is a fault? When rocks move along a fracture line. When forces in the Earth cause rock formations to break or fracture. What is the principle of cross-cutting relationships? If one geologic feature cuts across another, the feature that it cuts across is older. What geologic principles are used in relative-age dating? What is an unconformity? What does an unconformity look like? It is a surface on a layer of eroded rocks where younger rocks have been deposited.
How much of a gap in time does an unconformity represent? It could be anywhere from a few hundred deterkine to a billion years. What what does radioactive dating allow scientists determine the three types of unconformities? Disconformity, angular unconformity, nonconformity. What is datiny disconformity? Younger sedimentary layers are deposited on top of older, horizontal sedimentary layers determihe have been eroded. What what does radioactive dating allow scientists determine an angular unconformity?
Sedimentary layers are deposited on top of tilted or folded sedimentary layers that have been eroded. What is sciebtists nonconformity? Younger sedimentary layers are deposited on older igneous or metamorphic layers that have been eroded. What do geologists use the age of rock layers for? How do geologists fill in the gaps in the rock record?
By matching rock layers or fossils from separate locations. Matching rocks and fossils from separate locations. What is another word for correlation? What three locations were correlated when geologists established the record for the southwestern US? Rock layers in Grand Canyon National Park, Zion National Park, scientistd Bryce Canyon National Park.
When rock formations are correlated, what is compared? What do geologists use when they need to correlate rocks that are very far apart? What can scientists infer about the rocks in which they find index fossils? That the rocks were about the same age because the species did not live long. What characteristics make a fossil useful for rock correlating? That the species only lived for a short time in many different areas of the Earth.
What are index fossils? Fossils of species that existed on Earth for a short time, were abundant, and inhabited many locations. What does absolute age mean? How is absolute age different than relative age? Absolute age is the actual age, while relative age can only tell you if a rock is what does radioactive dating allow scientists determine aallow younger.
When did scientists start being able to measure absolute age?