Geology of Benmclcshire, 637 



came into the phase of prolonged interinittence, but was again 

 active in 1821. 



The other volcanoes of Iceland are Krabla, Eyafealla Jokul, 

 Eyrefa Jokul, Skeptaa Jokul, Kattlagiaa, Wester Jokul, 

 and Gullunge Syssel. All these have been the sources of 

 violent eruptions, and have spread their lavas throughout this 

 interesting island, which seems to be a mere vent of some 

 vast reservoir of heated lava. 



The only other situation in Europe in which we find an 

 active volcano is the Island of Jan Mayen, off the coast of 

 Greenland, which was active in the year 1818. When visited 

 by Captain Scoresby, the crater was about 500 ft. deep, and 

 2000 ft. in diameter. 



The continent of Africa does not offer a single example of 

 an active volcano, but in the islands they are very numerous : 

 these shall be noticed in our next communication. 



(To be continued,) 



Art. VIII. Contributions to the Geology ofBermchshire. By Ro- 

 bert DuNDAs Thomson, CM. and M.D., of the Honourable 

 East India Company's Service. [Read before the Berwick- 

 shire Naturalists' Club, December 21. 1831.] 



The parishes of Eccles, Greenlaw, Polwarth, and Long- 

 formacus include a narrow tract of country extending from 

 the Tweed to the Lammermoors ; and, small though this tract 

 may appear, it comprehends, as it were, a section of the 

 county of Berwick, includes all the fundamental rocks of the 

 county, and one or two which are peculiar to it. 



The order of the rocks, beginning at the surface, is, — 

 amygdaloid, new red sandstone, claystone porphyry, mag- 

 nesian limestone, greywacke, and old red sandstone. 



New Red Sandstone, — The banks of the Tweed, in the 

 greater part of its course through the Merse, appear to con- 

 sist of the rocks of this formation. The characteristic aspect 

 which it most generally assumes is that of a dark sandstone, 

 often highly indurated, but, when exposed, becoming soft and 

 slaty. An analysis of it shows that it contains about 25 per 

 cent of carbonate of lime : and from this circumstance, and 

 its external characters, it may be distinguished as a marly 

 sandstone. Its relative position with regard to other rocks 

 can be well seen at Lochton, where the north bank of the 

 Tweed is high and precipitous for about a quarter of a mile. 

 Here it alternates with a still more indurated variety, which, 



