The Quarterly journal of the Geological Society of London . ems, and part ^ l^BBQjm^e^^ of the Ehine glacier y^^y^^T^y^ reinforced that of the ^^ y^yy/ Linth, a8 Was pointed x Two lower lignite-bands exhausted out in the Geol. Mag. paper already quoted. According to Heer, the Uznach, Durnten,and Wetzikon deposits were parts of a former continuous lignite-bed, probably formed in an extensive lake. There is, however, notrace of continuity; moreover, the distance of about 20 milesbetween the two deposits and the difference of level (over 100 feet)between them militate against Heers assumption. Th
The Quarterly journal of the Geological Society of London . ems, and part ^ l^BBQjm^e^^ of the Ehine glacier y^^y^^T^y^ reinforced that of the ^^ y^yy/ Linth, a8 Was pointed x Two lower lignite-bands exhausted out in the Geol. Mag. paper already quoted. According to Heer, the Uznach, Durnten,and Wetzikon deposits were parts of a former continuous lignite-bed, probably formed in an extensive lake. There is, however, notrace of continuity; moreover, the distance of about 20 milesbetween the two deposits and the difference of level (over 100 feet)between them militate against Heers assumption. There can be nodoubt that these deposits, as also those near the Lake of Constance,were simply local and isolated peat-mosses formed on boulder-clay,1 1 The term boulder-clay denotes throughout this paper the comparativelythin layer of clay which, in the Swiss Alps, generally forms the lowest parts ofglacial deposits. It is essentially a product of abrasion, and corresponds to the Geschiebe-Lehm of Swiss geologists, this term being, in fact, simply a trans-. Vol. 51.] AND INTERGLACIAL DEPOSITS IN SWITZERLAND. 375 in stagnant pools and under climatic conditions very like those ofour own day. Such peat-mosses of post-Glacial age exist in abund-ance in the same locality, and always afford evidence of underlyingboulder-clay, whose impermeable nature is eminently favourable totheir formation. As is well known, peat is composed chiefly of the dead parts ofweeds and moss, whose capillary structure promotes their growthby the constant absorption of water from below. The pressure ofsand, gravel, and moraine subsequently deposited on the PleistoceneUznach, Diirnten, and Moerschwil peat-mosses, and the stoppage oftheir further growth by the exclusion of feed-water, converted themgradually into more or less slaty lignite. The quality of the ligniteimproves with the depth—that is, with the pressure to which thelignite is subjected, as is evidenced by the three superposed Uznachseams, of whi
Size: 1603px × 1559px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1840, bookidquarte, booksubjectgeology
