Dinosaur fossils can found rocks dating Sex chat teens 13 19
While everybody understands that black bears are related to grizzly bears and we can even figure they are related to extinct bears, lots of people wonder how scientists can be so sure that bears are related to salmon as well.One evidence is rock layersspecifically, what is called the geologic column.There are thousands upon thousands of layers in the earth's crust.However, scientists have grouped the layers into major groups.Basically, scientists have learned that rocks are stacked in layers containing fossils with the oldest fossils at the deepest layers, and the youngest, or most recent fossils, near the top. At the bottom of the timeline there are no fossils of modern animals.
This law of science tells us that dirt, mud, sand and other sediments are almost always deposited in horizontal layers.
As these sediments stack up vertically, they often harden, forming rock layers.