Till shores, coastal dunes, and varved clay plains
The West-Estonian Lowland has been called Terra Maritima — Land on the Sea, since the sea was the most important factor in the development of the area and still plays an important role. The shores here are low, mainly stony till shores. Coastal escarpments can be found on the Ramsi Headland of the Noarootsi Peninsula, in Pullapää (near Haapsalu) and on the Uisu limestone scarp on the Suur Väin Strait. In places sheltered from wave activity, one can see silt shores with mud accumulating on (clayey) fine-grained sediments. This is particularly characteristic of Haapsalu Bay and its small bights, although a mud deposit also covers the fine-grained sediments of the bottom of Matsalu Bay. Coasts with sand dunes are less frequent, and can be found mainly in the Riguldi–Põõsaspea–Nõva area.
Till shores and coastal dunes
Till shore abraded by sea waves is also the most widespread shore type in the northwestern part of the Pärnu Lowland, i.e. to the west of Pärnu. In the surroundings of Paatsalu village, the coastline is indented by inlets oriented south–west; the coastal sea there is spotted with small islands. At Tõstamaa the coast is characterised by southeast oriented inlets separated by small headlands. On the headlands and islands the dominant shore type is till shore, and on the bays, silt shore. In the surroundings of Audru and Pärnu, low-sodded shore dominates, alternating with beaches in places (Valgerand beach).
The most typical features of the southwestern coast of the Pärnu Lowland are abundant sandy shores and long ranges of shore ridges covered with sand dunes. The main range of coastal dunes begins within the city limits of Pärnu, becoming higher and more distinct towards the south. At Tahkuranna it splits in two, with a former lagoon of the Littorina Sea separating the two ranges. At present the lagoon has grown over with vegetation and its location is marked by the Tolkuse raised bog. The Soometsa dune system bordering the bog on the east was formed during the stage of Lake Ancylus; the dune system adjacent to the coast dates from the Littorina Sea stage. The dune system reaches its maximum height at Tõotusemägi Hill (ca 40 m above sea level) near Rannametsa village. Another higher dune is located nearby — Tornimägi Hill. The dune ranges are crevassed by several small rivers and streams that carry water from the paludified areas behind the dunes to the sea. The biggest of these is the Timmkanal River, which traverses the Tolkuse bog and connects the Ura River with the lower course of the Rannametsa River. Near Häädemeeste, the dune ranges join again and proceed as a single narrow and gradually lowering range down to Ikla village and from there on to Latvia. At Tahkuranna, in the valleys of the Timmkanal, Lemmejõgi and other rivers, outcrops of Devonian sandstone can be seen.
Varved clay plains
On the shores of Matsalu Bay, near Haapsalu, between Pärnu and Vändra, and in many other places in West Estonia, the relief is dominated by varved clay plains with an almost ideally flat surface. After the last retreat of the continental ice sheet, these areas were flooded by the water of the Baltic Ice Lake. Sedimentation of fine detritus followed a very regular pattern in this huge water body: slightly coarser and sandier material was deposited in the warm season and finer, more clayey material in the cold season. As a result of this process large clayey plains were formed, covering even the slightest unevennesses of the surface. Due to the above described sedimentation pattern, the clay here has a layered or ‘varved’ structure and is therefore known as varved clay. Each individual layer in this deposit can be identified as a summer or winter varve; one summer and one winter varve together make an annual varve. By counting all such layers in the varved clay deposit it is easy to determine the time that it has taken for the deposit to form.
Varved clay plains are covered with gley soils of relatively high productivity formed on a rich parent material. Tilling of these lands has often required drainage. Varved clay has been used in these neighbourhoods for making bricks for construction.Details about this article
Created: 29.05.2001 17:41
Modified: 28.09.2012 17:27