SUPPLEMENTARY NOTE A. 113 



horizontally, or approximately so, and the other to vertical 

 movements extending over wide geographical areas. More than 

 thirty years ago my attention was called to the latter class of 

 movements by the beautifully developed series of terraces in the 

 Burren of Clare, 'reaching to the height of nearly 1200 feet. 

 This particular instance I have ascribed to a slow upheaval of 

 the district above the sea, the surface of each terrace representing 

 the bottom of a coast- shore a plane of marine denudation and 

 an intermittent stoppage in the upheaval*. An examination 

 which I made in 1870 of the terraces of Lochaber resulted in my 

 becoming convinced that they are ancient sea-margins : 1495 feet 

 is the height usually stated of these terraces ; but I detected on 

 the flanks of Ben Nevis, and of the opposite mountains, the like 

 features, which must reach to an altitude of between 2000 and 

 3000 feet. Besides the raised shell-beaches standing at a com- 

 paratively low level on the coasts of Norway, terraces have been 

 lately observed and described by Daykins, which occur on the 

 Dovrefjeld, at heights of from 2000 to 3100 feet. Darwin's 

 account of the remarkable examples that occur in Patagonia, up 

 to the height of 1300 feet, leaves no doubt on my mind that they 

 have been formed by the action of the sea. Hector has described 

 vast terraces on both the eastern and Pacific slopes of the Rocky 

 Mountains, stretching from the Athabasca river to Mexico, and 

 rising one above another to heights ranging from 3500 to 

 4500 feet above the level of the sea. Well marked parallel 

 terraces are striking features in other parts of North America. 

 A series of " horizontal benches/' twenty in number, deeply cut 

 into the mountain-slopes, and situated at heights between 1100 

 and 2580 feet above the sea-level, extend over an area of 10,000 

 square miles both east and west of the Alleghanies of Pennsyl- 

 vania> Virginia, and Maryland. As properly remarked by Prof. 

 Stevenson, who has lately described them, "they can be no 

 other than sea-beaches marking stages in the withdrawal of the 

 ocean" f. The late Daniel Sharpe made known the occurrence 

 of lines of erosion on the inner and outer flanks of the Swiss 

 Alps, at about 4800, 7500, and 9000 feet above the sea. And, 

 to finish what could be made a much longer list, Rudolph 

 Griesbach has described terraces in Natal lying at heights 



* See < The Geologist,' vol. vi. pp. 172, 173 (1863). 

 t American Philosophical Society, August 15, 1879. 



