The geological evidence is clear, Devils Tower is a rock structure and was not a giant tree.

How was Devils Tower formed?

The simplest explanation is that Devils Tower is a stock—a small intrusive body formed by magma which cooled underground and was later exposed by erosion (Figure 1). In 1907, scientists Darton and O'Hara decided that Devils Tower must be an eroded remnant of a laccolith.

Did Devils Tower used to be a volcano?

Although magma formed Devils Tower, it was probably never part of a volcano. Most geologists agree that Devils Tower is an igneous intrusion, a place where magma from the Earth's mantle welled up between chunks of sedimentary rock.