BUFFALO SOCIETY OF NATURAL SCIENCES 1 73 



.upon Silurian, Ordovician or even older strata, including the meta- 

 morphic rocks of the Southern Highlands of Scotland. What has 

 been taken as the Caledonian Old Red in the cases where it has been 

 supposed that a passage exists is % in reality a series of quite different 

 age" (Goodchild, 80, 598, 599). As further evidence of the great 

 break between the two systems Goodchild adds that the Lanarkian 

 rocks shared in all of the tremendous disturbances to which the 

 Siluric rocks were subjected and that "these disturbances had ceased, 

 and had been followed by prolonged denudation, long before the old- 

 est member of the Caledonian Old Red was laid down. Hence it 

 results that the great unconformity, so often referred to, passes above 

 what is left of the Lanarkian rocks. There is no clear evidence of 

 any unconformity below them" (Goodchild, 80, 599). 



Thus from the many sections described in the Scottish literature 

 and especially from the authoritative statement of Goodchild, there 

 seems to be good reason for believing that there was a great uncon- 

 formity at the end of the Siluric, caused in part by profound tectonic 

 disturbances, and that following upon these there was a long period 

 of erosion before the earliest of the Caledonian deposits were laid 

 down. These were of great thickness, amounting in some places to 

 20,000 feet. As to the origin of the series Goodchild says: "There 

 appears to be evidence of a satisfactory nature that the whole of the 

 vast formation was accumulated under continental conditions, partly 

 in large inland lakes, partly as torrential deposits of various kinds, 

 partly as old desert sands, and partly as the results of extensive 

 volcanic action" (80, 596). 



A brief review of the lithological characters and distribution of 

 the Caledonian Old Red series will show most clearly that the rocks 

 throughout are of continental origin. The lowest member, division 

 1, consisting of sandstones and conglomerates, is often wanting alto- 

 gether, the overlying volcanics being the first of the series to be 

 present. At the Falls of Clyde, near Lanark, Lanarkshire, these 

 lower beds are, however, to be seen, and they are also found in a few 

 other localities. Generally, the volcanics rest immediately and with 

 a violent unconformity upon various pre-Devonic formations. It is 

 these lavas which are seen in the Ochils and Sidlaw Hills, in the Pent- 

 lands and in the vicinity of Oban, at St. Abb's Head and also in the 

 Cheviot Hills. In their greatest development in the Perth and Forfar 

 Hills the volcanics may well reach several thousand feet in thickness, 

 but they thin away toward the north and northeast and pass into 



