It is the longest Devonian sandstone outcrop in Estonia, which, according to 2001 measurements, is about 930 meters long.
Starting from the southern edge of the city and moving to the central square, you can see 11 outcrops separated by overgrown sections, which are usually 1–5 meters from the waterline, mostly separated by a strip of sand. However, if the water level rises during high water, the waves break the outcrop, which has created many caves in the sandstone. The larger ones exceed 1.5 meters in height and reach depths of up to 6 meters.
The height of the outcrops is mostly 2–4 meters, the maximum height is 9 meters.
The southernmost and highest part of the outcrop has been under nature protection since 1959.
Outcrop offers a good nesting place for shore swallows, whose largest colony in Estonia is located on the Kallaste outcrop.
Fossils of ryegrass, acanthodes, jaws, lungfish and amphibians have been found in the outcrop.