Geology and Mineralogy. 159 



islands both northeast of the deep region, near Guam, and also 

 of large size, to the southwest and southeast, not three degrees 

 off; the former, those of an extension of the Pelew range, and the 

 latter, islands of the Caroline Archipelago. J. d. dana. 



2. The Physical Features of Scotland, by Professor James 

 Geikie. — This excellent paper is illustrated by an orographic 

 map of Scotland which is necessary to its full appreciation. The 

 author condemns the "statement so frequently repeated in class- 

 books and manuals of geography, that the mountains of Scotland 

 consist of three (some say five) ranges." He observes that it is 

 divided into three parts " the Highlands," the Central Lowlands 

 and the Southern Uplands ; and defines the Lowlands (which are 

 the southern limits of the Highlands and northern of the Southern 

 Uplands) as extending from Stoneham in a nearly straight south- 

 west direction along the northern outskirts of Strathmore to Glen 

 Artney, and thence through the lower reaches of Loch Lomond 

 to the Firth of Clyde at Kilcreggan. The mountains " are 

 merely monuments of denudation," "relics of elevated plateaus 

 which have been deeply furrowed and trenched by running water 

 and other agents of erosion." The straightness of the southern 

 boundary of the Highlands " is due to the fact that it coincides 

 with a great line of fracture of the earth's crust ; on the north 

 side are hard and tough slates and schists, on the south sand- 

 stone strata prevail." Looking across Strathmore from the 

 Sidlaws or the Ochils, the mountains seem to spring suddenly 

 from the low grounds at their base, and to extend northeast and 

 southwest as a great wall-like rampart. " The mean height of the 

 Highlands above the sea is probably not less than 1500 feet;" 

 peaks rise to a height of nearly 3500 feet. Any wide tract of 

 this Highland region " viewed from a commanding position looks 

 like a tumbled ocean in which the waves appear to be moving in 

 all directions. But the masses are broad, generally round- 

 shouldered, often somewhat fiat-topped, with no great disparity 

 of height among the dominant points. The relationship and the 

 forms are the result of denudation ; the mountains are " monu- 

 ments of erosion," — they are the wreck of an old table land — the 

 upper surface and original inclination of which are approximately 

 indicated by the summits of the various mountain masses and 

 the directions of the principal water-flows. 



A similar general conclusion is drawn from the Southern Up- 

 lands ; that " the area is simply an old table-land furrowed into 

 ravine and valley by the operation of the various agents of 

 erosion." 



In view of such facts it is not surprising that Scotch valleys 

 and mountains should have given to Hutton right ideas on moun- 

 tain sculpturing, and have led him to the opinion he brings out 

 in his memoir on the Theory of the Earth (R. Soc. Edinb. 1778, 

 and 8vo, 1795), that mountain forms are due to subaerial denuda- 

 tion after an elevation of a region by the earth's central heat. 



Professor Geikie illustrates the subject with much interesting 



