10 



other " measures," with the trap rocks overlying, are sufficiently hard 

 and coherent to have withstood the attrition of a lengthened journey. 

 So numerous and varied are the contents of the boulder or Till beds, 

 that within the limits of Glasgow, from the cuttings in the hill 

 sides for the foundations of the houses, nearly a complete collection 

 of Scottish rocks may be made; granite, gneiss, mica, clay and chlo- 

 rite slates, quartz rock, porphyries, old red sandstone and conglo- 

 merate, coal sandstone, ironstone, limestone, and a vast variety of 

 traps are all turned out from the same cutting. The recent exca- 

 vations on Woodlands' hill for the roads and buildings of the new 

 park have exposed such assemblages ; a noted locality, which excited 

 great interest during the meeting of the British Association in 

 1840, and has been often since referred to, is Bell's park, near the 

 Caledonian Railway station, north side of the city. The great ma- 

 jority of these boulders are rounded and smooth, but many of them 

 are striated and grooved ; and when the covering of Till is removed, 

 the rocky bed on which it rested has also been found in several cases 

 to present the same scratched and grooved surface. A good ex- 

 ample occurred in Bell's park ; but the rock has been quarried. 

 In the neighbourhood of the Town's Hospital some of these striated 

 blocks may still be seen. Many were turned out from the cuttings 

 for the roads and buildings of the new park. 



1 1 . Grooved and scratched rocks were observed near Glasgow by 

 Colonel Imrie in 1812 (Wer. Mem., ii., 36), and ascribed by him, and 

 by subsequent observers, to the action of the rocks on one another 

 during transport by currents of water sweeping the surface; and 

 were classed under the head of Diluvial phenomena, being supposed 

 to have been produced by the Deluge, or several successive floods 

 in different periods. About 1840, however, they began to be re- 

 ferred to the action of glaciers, or the agency of floating masses 

 of ice, which carried the boulders, grinding them down and marking 

 the surfaces across which they passed. Mr. Smith's remarkable 

 discovery of Arctic species in the Clyde shelly deposits associated 

 with Till and boulders is strongly corroborative of this latter 

 view, and indicates a prevalent low temperature immediately 

 preceding that condition of things during which the British 

 seas were furnished with their existing testacea. To this view 

 the opinions of geologists now chiefly lean; but the subject is 

 yet beset with difficulties. Several considerations must be carefully 

 attended to; the impression of the surface markings must have 

 been posterior to the rounding process the far transported masses 

 are the most rounded, and there seem evidently several periods 

 in the Till deposit, as already noticed. May it not hence be sup- 



