56 THE SAND STEAXD FLOEA 



the Gulf. The coast is here unsheltered by anj' islands; and the shore 

 is exposed to the full force of the open sea. The prevailing winds are 

 westerly and southwesterly', that is, those which have a free passage 

 along the whole stretch of the Gulf from the Baltic. They meet no 

 obstacles in their wa}', and they strike the land with their full intensity. 

 On this coast a series of dunes have been formed following the coast 

 continuously for about 80 km. Although every sign of tides is absent, 

 the sea is very seldom or never quite calm. The constant breakers and 

 the great difference between the high and low water caused by winds 

 have developed the sand formations of this district. Some of the dunes 

 are smaller and some larger; some of them are still drifting before the 

 high winds, constantly changing their form and their position, en- 

 CToaching more and more on the land. Others again are in ridge form, 

 covered with vegetation, and are stable. 



This sand consists of quartz of a yellow-white color, mixed with 

 felspar and mica. The size of the grains is 0.3-1 mm., and they are 

 sometimes larger, up to 3 mm. On this coast, the development of the 

 dunes is promoted by human agency, the natural forests being destroyed 

 and the larger pebbles, which have been left by the wind on the shore, 

 and which retard the advancing sand thrown up by the waves, are col- 

 lected and transported to St. Petersburg for road-making purposes and 

 thus the sand is given a full opportunity to spread. The form of these 

 dunes is varying. They consist mostly of long hills of very different 

 dimensions, some almost round, others nearing but never completely 

 assuming the horse-shoe form. 



These dunes have been studied by Soholoff^) and Theslefp) , and 

 my own observations were made during several visits in Maj', August 

 and October, 1898. 



On the Pinnish south coast, which is rocky, there are only a few 

 sand formations. Sandy beaches of the same character as those of the 

 Swedish east coast near Stockliolm were studied, near the city of 

 Helsingfors, during 1893 — '99 and on the coast of the province of 

 J^yland, 1891 — '92, and 1898— '99. On the Hango peninsula there 

 is a smaller dune district which was made the subject of detailed inves- 

 tigations in June 1895, in July 1896, in August and September 1897, 

 in April, August and September, 1898, and in August, 1899. The sand 

 is here of glacial origin, having been redeposited by waves and wind. 

 The salinity of the sea water was 0.6% at a temperature of +14.0°C. 



1) Die Diinen. Berlin, 1894. 



2) Dynbildnlngar i ostra Finland. — Med. Geogr. For. Finl. p. 36 — 77. 1895. 



