216 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 2 



rope gives clear evidence of continental conditions existing over the 

 northern area while marine conditions obtained to the south. The 

 line of separation may be roughly traced from the British Channel 

 eastward to the Ural Mountains. Oscillations of this shore line 

 through the period are shown by the interdigitation of the continental 

 and marine deposits in several places. Wherever the Old Red Sand- 

 stone type of deposit occurs in the British areas it consists of con- 

 glomerates, breccias, grits, sandstones, and shales, with impure lime- 

 stones or cornstones in places. 



The whole series is such as could only have been derived from an 

 area in which the rocks were dominantly of granite type. 



Heard and Davis have published a full account of the Old Red 

 Sandstone of the Cardiff district, in which they show that mineralog- 

 ically it bears a striking resemblance to the Torridonian and the 

 Millstone grit of Yorkshire, and they conclude that it must have 

 been derived from some pre-Cambrian area lying to the northwest, 

 and its accumulation was under similar conditions to those which 

 I have suggested for the Millstone grit of Yorkshire. The exten- 

 sion of the Old Red Sandstone continental area, with its character- 

 istic flora and fauna, to Bear Island and Spitsbergen is shown by 

 the occurrence there of thick beds of red micaceous sandstone (the 

 Liefde Bay system) which has yielded Cephalaspis^ Scaphaspis, and 

 plant remains of Old Red Sandstone age. 



In Greenland a red sandstone rests unconformably on ancient 

 folded rocks. This sandstone has furnished no organic remains, so 

 that its age is not definitely known, but everything points to its 

 being the same as the Liefde Bay system (Old Red Sandstone) of 

 Spitsbergen. This sandstone which is of great thickness occurs both 

 on the east and west coasts, and on the west it is accompanied by 

 porphyry. 



In North America Old Red Sandstone beds are met with in the 

 Northeastern States, in Gaspe, and New Brunswick. These repre- 

 sent delta deposits laid down in the northern part of tlie great 

 Appalachian trough from a land mass lying off the present coast 

 line of eastern North America. The Gaspe sandstones have a thick- 

 ness of over 7,000 feet, while along the southern coast of New Bruns- 

 wick similar rocks attain a thickness of 9,500 feet. In the interior 

 these clastic deposits pass into marine sediments of Devonian type, 

 consisting of shales and limestones. 



VI. THE CARBONIFEROUS PERIOD 



The clastic deposits of this period cover an enormous area in 

 the British Isles to-day, and that area would need to be enlarged 

 very much if we consider the conditions at the end of Carboniferous 



