On some Erratics in the Boulder-clay of Cheshire. 207 



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 &c, 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 entirely covered with 

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

 and those of the tributary valleys. The glacial striae coincide in 

 direction with that of the respective valleys, or are in direct con- 

 nection 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 striae have 

 been removed, probably by currents of water holding sand in sus- 

 pension. Above these there is a boulder- clay containing a larger 

 proportion of sand and gravel than the boulder-day 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, &c. caused by changes in the exten- 

 sion 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 connection with this 

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

 the granitic and volcanic rocks the process differed 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 moraine in the 

 neighbourhood of Shap, where also rocks of volcanic 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 



