DEPRESSION OF GREENLAND. 327 



Similar evidences of elevation in recent times are found in the Medi- 

 terranean. Not only is the shore of Tunis becoming too shallow for the 

 approach of ships, but the coasts of Sicily, Sardinia, and parts of Tus- 

 cany tell the same story in the elevation of shell-beds, which sometimes, 

 as in Sardinia, contain pottery at a height of 200 feet above the sea. 

 The shores of the Adriatic, however, are undergoing depression. 



Mr. Kinahan, in his " Geology of Ireland," has described numerous 

 raised sea-beaches and sea-margins, and others are well known on the 

 Devonshire coast and in Cornwall, where Mr. Ussher has referred to 

 them at Mount Edgecombe near Plymouth, Looe Island, St. Austell's 

 Bay, Falmouth, south of the river Helford, Coverack Cove, &c., &C. 1 



Depression of Land. Depression is inseparable from elevation, 

 just as every synclinal fold is a portion of an anticlinal fold. Hence, 

 beyond the geographical limit of upheaval a coast is found to be sub- 

 siding, and the regions where this condition is seen are necessarily 

 adjacent to those which are being raised. On the Greenland coast, 

 in Igalliko Fiord, in 1779 a small rocky island was entirely sub- 

 merged at spring-tides, yet the walls of an old Norse house remained 

 visible. Fifty years later only the ruins rose above the water. In 

 many places farther south, in lat. 62, 63, 64, and 65, the ruins of 

 dwellings are seen which are overflowed by the tide. The Moravian 

 Mission settlements moved inland the posts on which the large 

 boats are kept. In Disco Bay, Dr. Kobert Brown records that a 

 blubber boiling-house was built about eight miles from the shore on 

 an islet, which sunk gradually till the water entered the floor of 

 the house at high tide, when it had to be abandoned. 



In the Mediterranean, the standing pillars of the temple of Jupiter 

 Serapis, in the Bay of Baia3, are an example of the extreme steadi- 

 ness with which earth-movements both of elevation and depression 

 take place. 



But the most striking instances of change of level at the present 

 day are recorded by the phenomena of barrier reefs and atolls. 



On our own shores depression is proved by submerged forests, as 

 at Looe, Fowey, Falmouth, Mounts Bay, Padstow in Cornwall, Por- 

 lock in West Somerset, and many places in Norfolk, Sussex, &c. 



The entire history of the strata is a record of a few grand oscilla- 

 tions of level, from which it has resulted that the same area has been 

 alternately covered by fresh-water deposits accumulated upon land, 

 and marine deposits which were superimposed when the region sunk 

 beneath the sea. 



Is Steam a Cause of Upheaval or a Consequence 9 it is con- 

 ceivable that water might be conducted, in consequence of some 

 accident of the earth's crust, to the required contact with the heated 

 rock at some moderate depth below the surface, and thus high-pres- 

 sure steam be generated and accumulated until disturbance comes. 

 A gaseous force of some kind may be supposed ; thus the melted rock 

 is pressed up to the very summits of Tenerifle and the Andes ; and 

 masses of stone hurled out of Vesuvius have fallen at a distance of 

 1 Geol. Mag., 1879 



