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What is the theory of geological change?
Lesson Summary. The two main theories about the history of Earth are catastrophism and uniformitarianism. Both theories acknowledge that the Earth’s landscape was formed and shaped by natural events over geologic time.
What is an example of geologic change?
Wind, water, and ice erode and shape the land. Volcanic activity and earthquakes alter the landscape in a dramatic and often violent manner. And on a much longer timescale, the movement of earth’s plates slowly reconfigures oceans and continents. Each one of these processes plays a role in the Arctic and Antarctica.
How did the geologist describe the rate of geologic change?
The geologic time scale was developed after scientists observed changes in the fossils going from oldest to youngest sedimentary rocks. Later, scientists used absolute dating to determine the actual number of years ago that events happened. The geologic time scale is divided into eons, eras, periods, and epochs.
What geological age do scientists say we are in today?
Officially, the current epoch is called the Holocene, which began 11,700 years ago after the last major ice age.
Why are scientists so interested in geologic events?
One of the interesting things about those events is that they occur today in the same way that they have in the past. Scientists look at modern-day geologic events—whether as sudden as an earthquake or as slow as the erosion of a river valley—to get a window into past events.
How are scientists able to tell the age of rocks?
The decay of potassium to argon, uranium to lead, and one isotope of lead to another are some common yardsticks used to date very old rocks. These dating methods allow scientists to put real ages on rocks with astonishing accuracy. By about the 1950s, most of the Geologic Time Scale had real dates (described as “years before the present time”).
How are geochronologists used to date the Earth?
Every year, geochronologists (GEE-oh-kron-OL-oh-gizts) — scientists who specialize in dating geologic ages — improve the methods to zoom in more accurately. They can now distinguish events that occurred just a few thousand years apart, back tens of millions of years ago.
What are the forces that change the geography of the Earth?
Geologic forces are forces that can change the Geography of the land, caused by powerful tectonic forces within the earth. What is the definition of uniformitarianism? The geologic principle that the same geologic processes that operate today operated in the past to change Earth’s surface.