28 Charles Maclaren, Esq., on the Existence of 



masses of snow (avalanches), have swept parts of it away. 

 Instead of a continued terrace, therefore, it presents a suc- 

 cession of little knolls or protuberances, sometimes in con- 

 tact at the bottom, sometimes separated by wide gaps, but 

 in general running nearly in one line. That line is not ho- 

 rizontal, but inclined to the foot of the loch at a low angle, 

 varying from two degrees to ten. There are three, or per- 

 haps four, of these terraces. In some parts they are obscure 

 and equivocal, but in others very distinct. The higher ones 

 generally overlap the lower, so that two terraces, the one a 

 hundred or two hundred feet below the other, are found at 

 some parts, for the space of a furlong. Sometimes the upper 

 seems to unite with and merge into the lower. Nos. 1 and 2 

 present this appearance. But they succeed one another, much 

 in the manner indicated in the diagram. The highest, 1 , is 

 about 550 feet of vertical height above the loch at its north 

 end, and may be traced for about a mile. The lowest, 4, is ex- 

 ceedingly well marked above the villa of Brownfield, where 

 it forms a terrace nearly level, and more than 100 feet in 

 breadth. It descends pretty rapidly, and at Leruel is about 

 60 feet above the loch. Its course southward is interrupted 

 by a ravine behind Altdonach, beyond which it reappears, and 

 finally merges into the projecting point of Row, with an ele- 

 vation of 40 feet, much in the same manner apparently as the 

 lateral moraine merges into the terminal in a Swiss glacier. 

 The openings cut through the terraces exhibit their com- 

 position. They consist chiefly of clay, mixed with fine chips 

 of mica-slate, along with gravel, and with blocks of various 

 sizes. Some of the latter are of great magnitude, 5, 8, or 10 

 cubic yards. These are seldom much rounded, and nineteen 

 out of twenty are of the rock of the district. Some are buried 

 in the soil, and only discovered in the sections made by the 

 torrents ; others protrude through the turf. The proportion 

 of soft matter, clay or sand, was larger than I expected to 

 find, for Agassiz's plates represent the lateral moraines of 

 existing glaciers as' chiefly formed of rocky fragments. But 

 on referring to his book, the idea his description conveys is 

 not inconsistent with the facts I observed. He says — " In 

 moraines, properly so called, that is to say, upon the sides 



