How many mass extinctions has the been on Earth.according to the geologic record? 3 is 7 10

## Step 1<br />The question is asking for the number of mass extinctions that have occurred on Earth according to the geological record. Mass extinctions are events in which a significant percentage of all life forms on Earth become extinct in a relatively short period of time.<br /><br />## Step 2<br />The geological record shows that there have been five major mass extinctions in Earth's history. These are:<br /><br />1. Theician-Silurian extinction, which occurred approximately 443 million years ago.<br />2. The Late Devonian extinction, which occurred approximately 359 million years ago.<br />3. The Permian-Triassic extinction, also known as the "Great Dying", which occurred approximately 252 million years ago.<br />4. The Triassic-Jurassic extinction, which occurred approximately 201 million years ago.<br />5. The Cretaceous-Paleogene extinction, which occurred approximately 66 million years ago.<br /><br />## Step 3<br />These events are significant because they have shaped the course of evolution and the development of life on Earth.