330 Mqjorts and Proceedings — 



shown that much gold was derived originally from veins in the older 

 or Silurian rocks, and that some of that met with in the newer 

 system occurred in conglomerates or other detrital beds. But there 

 are also gold-bearing quartz-veins intersecting the latter. 



3. " On some Erratics in the Boulder-clay of Cheshire, etc., and 

 the Conditions of Climate they denote." By Charles Eicketts, M.D., 

 F.G.S. 



The author stated that the glacial phenomena of the valley of the 

 Mersey indicate that the country has been entirelj'^ covered with ice 

 and snow, resulting solely from the snowfall on its water-slopes and 

 those of the tributaiy valleys. The glacial striee coincide in direction 

 with that of the respective valleys, or are in direct connexion with 

 the contour of the ground. The bottoms of the valleys are usually 

 filled to some extent with irregularly stratified sands and gravels, 

 containing erratic pebbles from which all strise have been removed, 

 probably by currents of water holding sand in suspension. Above 

 these there is a boulder-clay containing a larger proportion of sand 

 and gravel than the boulder-clay proper. The flanks of the valleys 

 are covered with unstratified sand or fragments of sandstone derived 

 from the Trias, probably left by glaciers as submarine moraines. 

 The whole is overlain by the true boulder-clay, an unstratified 

 reddish-brown clay containing erratics derived from different and 

 distant localities. This clay originated in the grinding-action of the 

 glaciers upon the neighbouring rocks, and was carried out in the 

 form of mud by subglacial streams of water. The contained pebbles, 

 many of which are smoothed, flattened, scratched, and striated, were 

 carried by and dropped from icebergs and floating ice ; they are so 

 abundant as to indicate that the bay of Liverpool was densely packed 

 with ice. 



The author noticed the occurrence in these beds of masses of 

 contemporaneous sands, gravels, etc., caused by changes in the ex- 

 tension of the glaciers, and described a large series of erratics derived 

 from granitic, volcanic, Silurian, Carboniferous, and other rocks 

 covered with striae and other glacial markings, and also affording 

 evidence of subsequent exposure to weathering before they were 

 floated away and dropped into the clay. In connexion with this 

 weathering of the boulders, the author remarked that in the case of 

 the granitic and volcanic rocks, the process diifered greatly in degree, 

 extending in some granites to the separation of each individual 

 grain throughout the whole mass, and he called attention to the 

 occurrence in Ireland of fragments of disintegrated granite and trap 

 imbedded in moraines, eskers, and Boulder-clay, and to that of 

 Wastdale-Crag granite similarly decomposed in the moraines in the 

 neighbourhood of Shap, where also rocks of A^olcanic origin have 

 become weathered in the same way as some in the Boulder-clay of 

 Cheshire. Fragments of limestone also show traces of erosion, 

 while others have been split into two or more pieces since their 

 glaciation, phenomena also observed in moraine-accumulations in 

 limestone-districts. Similar phenomena occur in the case of slaty 

 and other stratified rocks. Some limestone pebbles have been per- 

 forated by Mollusca and other marine animals. 



