In Estonia distribution of limestone is connected with Ordovician and Silurian periods. This limestone here is one of the oldest in the whole World. The total thickness of limestone deposits varies from a couple of dozens metres in North-Estonian cliff up to 400 metres in South-Estonia.
Limestone outcrops are exposed in about half of Estonian territory. In the Northern coast, norward from the cliff, Cambrian deposits are exposed and limestone is missing altogether. In South-Estonia limestone deposits are covered by Devonian sandstones. Limestone may also be found in South Estonia, occurring as erratic boulders or among postglacial sediments (gravel). Some few limestone erratic boulders have moved with glacial cover in the opposite direction – from Estonia to Finland.