The Externsteine are located on the northeastern slope of the Teutoburger Wald.
They are a natural outcropping of sandstone in a region that is otherwise largely devoid of rocks.
The formation stretches for several hundred metres.
It starts inside the forest with some rocks that are mostly covered by soil.
It terminates in a series of 13 highly visible and mostly free-standing pillars.
For scientific purposes, these have been numbered I-XIII from northwest to southeast with the most imposing being stones I-V. The largest is rock I (subdivided into Ia and Ib), also known as the Grottenfels due to its cave.
The next one, II, is also known as Turmfels (tower) and rises 37.5 m (123 ft) above the surrounding area.
Rock III is called Treppenfels (stairs).
A large gap separates rocks III and IV.
The latter is also known as Wackelsteinfelsen due to a loose boulder (now fixed in place) at its top.

The geological formation consists of a hard, erosion-resistant sandstone (so-called Osningsandstein), laid down during the early Cretaceous era about 100 million years ago, near the edge of a large shallow sea that covered large parts of Northern Europe at the time.
About 70 million years ago, these originally horizontal layers were folded to an almost vertical position.
The resulting cracks in the stone offered ample scope for various forms of weathering.
Thousands of years of erosion washed the rocks from the surrounding soil and then formed the surface of the stone.

The pillars have been modified and decorated by humans over the centuries.
Most of these alterations are on the southwestern side.

The pond that currently lies at the foot of the formation is artificial and was created in the 19th century.
The Externsteine are located on the northeastern slope of the Teutoburger Wald. They are a natural outcropping of sandstone in a region that is otherwise largely devoid of rocks. The formation stretches for several hundred metres. It starts inside the forest with some rocks that are mostly covered by soil. It terminates in a series of 13 highly visible and mostly free-standing pillars. For scientific purposes, these have been numbered I-XIII from northwest to southeast with the most imposing being stones I-V. The largest is rock I (subdivided into Ia and Ib), also known as the Grottenfels due to its cave. The next one, II, is also known as Turmfels (tower) and rises 37.5 m (123 ft) above the surrounding area. Rock III is called Treppenfels (stairs). A large gap separates rocks III and IV. The latter is also known as Wackelsteinfelsen due to a loose boulder (now fixed in place) at its top.
The geological formation consists of a hard, erosion-resistant sandstone (so-called Osningsandstein), laid down during the early Cretaceous era about 100 million years ago, near the edge of a large shallow sea that covered large parts of Northern Europe at the time. About 70 million years ago, these originally horizontal layers were folded to an almost vertical position. The resulting cracks in the stone offered ample scope for various forms of weathering. Thousands of years of erosion washed the rocks from the surrounding soil and then formed the surface of the stone.
The pillars have been modified and decorated by humans over the centuries. Most of these alterations are on the southwestern side.
The pond that currently lies at the foot of the formation is artificial and was created in the 19th century.
Externsteine