The Mashan Stone Forest is located about 7 kilometers west of Jimo City, Qingdao. It consists of four connected mounds, shaped like a saddle, so it is also called "Ma'an Mountain". The highest peak has an altitude of 211 meters. Andesite porphyrite is abundant on the mountain. Most of it is gray-green or gray-brown and was formed by magma gushing out of the earth's surface and condensing about 100 million years ago. In the southwest of the mountain, there are square columnar joints. The diameter of the cross-section of each column is about 1 meter, and the height is about 30 meters or more.

They stand upright and are closely arranged, just like a dense forest, which is magnificent. Hence the name "Mashan Stone Forest". Columnar joint stone forests usually develop in basalt and are generally in the shape of hexagonal or pentagonal columns. However, the Mashan Stone Forest develops in andesite and is square-shaped, which is relatively rare in geology. Besides the four connected mounds, there is another small hill on Mashan. Locals customarily call it "Small Earth Hill". Before the establishment of the Mashan National Geological Park, this small hill was the source of building stones for local people. The stones produced here were of excellent quality, and local people called them "Mashan Stones". Today's "Mashan Stone Forest" landscape is the cross-section of this small hill.