3 1 Geological Society : — Dr. Forcham mer on Changes 



Forchammer, Phil. Doct. Copenhagen, Foreign Member of the 

 Society. 



The author referring to the observations of Mr. Lyell and of Mr. 

 Nilsson, on the unequal elevations of Sweden and subsidences of 

 Scania ; as proving that not only does elevation go on at a different 

 rate, but that motion takes place in opposite directions, adduces, as 

 instances of similar phenomena, the islands of Saltholm and of Born- 

 holm as well as the Danish coast of the Sound. The island of 

 Saltholm opposite to Copenhagen, and hardly five feet above the 

 level of the Sound, being mentioned from the thirteenth century 

 as a source of income to the chapter of Roeskilde; must have been 

 elevated at a slower rate than Bornholm, which rises about one foot 

 in a century ; for if it were now to sink only two feet a very small 

 portion of the island would be left. 



On the Danish coast however of the Sound, six miles to the north 

 of Copenhagen, a well characterized beach is observed, six feet 

 above sea-level ; hence the author infers that the change of level on 

 the Danish, proceeds in a different proportion from that on the Swe- 

 dish shore; which he ascribes to the slight earthquakes so frequently 

 felt in Sweden, but never observed in Denmark. 



With respect to the Danish island of Bornholm, the author ob- 

 serves, that its whole eastern shore is composed of a granitic rock, 

 rising abruptly out of the sea, and covered to the height of 250 feet 

 by a stiff loamy soil, containing numerous fragments of the slates 

 and limestones of the transition formation ,• of which the calcareous 

 specimens may easily be traced to the island of Gothland. From these 

 facts, and the absence of the plutonic rocks so frequent in the boul- 

 der formation of Denmark, and from the absence of this clayey 

 loam on the western side of the granitic ridge; he conceives that it 

 is the result of a violent inundation from the north-east of the Bal- 

 tic. The effects of this may be seen both in the form of the Da- 

 nish coast, and in the deposits of sand which cover a great part of 

 Denmark ; but which have been evidently swept away from the 

 more easterly beds of the boulder formation. 



At a height of about forty feet may be observed the first beach 

 formed on Bornholm : wherever by the receding of the granitic 

 mountains from the coast, small bays were formed, these became 

 choaked up by the granitic pebbles of the beach, and small ponds 

 were thus formed and separated from the sea ; and in the course 

 of ages became filled up with peat. This peat moss is separated 

 from the sea by a beach of small breadth, ten feet high, sloping at 

 an angle of 15°, and abutting on a horizontal plain, 160 feet in 

 breadth, formed entirely of beach stones. Beyond this is a second 

 plain, 100 feet broad, which slopes to the sea at an angle of 9° to 10°, 

 and is followed by the present beach sloping at an angle of 12° to 

 13°. The pebbles of all are similar in size, and composed of the 

 same granite as the solid rock. 



The author, referring to the existence on the sloping beach of 

 graves, marked only by a ring of stones, and to the testimony of an- 

 tiquaries, that it was the custom to bury Christians on the beach, 

 where the land and sea separated, about the year 900 ; obtains ma- 



