356 ON ALLUVIAL FORMATIONS, 



of the Baltic. The lands added to these islands of geest 

 are in most part composed of the sand of the sea, the 

 land-waters there being very inconsiderable ; and to the 

 south of them have been formed several islands of the 

 same nature, the chief of which are Laland and Falster, 

 near Seeland. These, like the marsh islands in the North 

 Sea, are sand-banks accumulated by the waves, and, 

 when covered with grass, continuing to be farther raised 

 by the sediments deposited between its blades. In the 

 Baltic, where there are no sensible tides, such islands 

 may be inhabited without dikes, as well as the extensions 

 of the coasts ; because, being raised to the highest level 

 of that sea, while their declivity under water is very 

 small, and being also more firm in their composition, the 

 waves die away on their shores ; and if, in any extra- 

 ordinary case, the sea rises over them, it leaves on them 

 fresh deposits, which increase their heights. These soils 

 are all perfectly horizontal, like those added to the coasts 

 of the Continent. 



Some of these islands approach entirely, or in part, 

 to the nature of that of Rugen. This island of Seeland, 

 on that side which is called Hedding, has a promontory 

 composed of strata of chalk with its flints. The island of 

 Moen (or Mona), on the south of the latter, has a simi- 

 lar promontory near Maglebye and Mandemark ; and the 

 island of Bornholm, the easternmost of those belonging 

 to Denmark, contains strata of coal, covered by others 

 of sandstone. Phenomena like these, evident symptoms 

 of the most violent catastrophes at the bottom of the an- 

 cient sea, proceeding, as I think I have clearly shewn, 

 from the subsidence and angular motions of large masses 

 of strata, which must have forced out the interior fluids 

 with the utmost impetuosity, it is not surprising that so 



