Geologists have divided the geologic time scale using evidence compiled using stratigraphy, which is the study of __ layers of igneous rock plate tectonics tree rings layers of sedimentary rock

## Step 1<br />Stratigraphy is a branch of geology that studies the physical characteristics of rock layers and their relative ages. It is used to understand the sequence of events in Earth's history.<br /><br />## Step 2<br />Stratigraphy does not focus on igneous rocks, plate tectonics, or tree rings. These are all important aspects of geology, but they are not the primary focus of stratigraphy.<br /><br />## Step 3<br />Stratigraphy is primarily concerned with sedimentary rocks. These rocks are formed from the accumulation of sediment, which can include fragments of other rocks, minerals, and biological material.<br /><br />## Step 4<br />By studying the layers of sedimentary rocks, geologists can understand the sequence of events that occurred over time. This includes the formation of mountains, the movement of continents, and the evolution of life.