756 



THE WONDERS OF GEOLOGY. Lect. VIII. 



an altitude, that rest unconformably on a base of gneiss."* 

 South of the Grampians, Devonian strata underlie the car- 

 boniferous system of Fifeshire ; and a zone of these deposits 

 skirts the southern flank of those mountains, from Stone- 

 haven to the Frith of Clyde ; and constitutes, with intrusive 

 trap rocks, the Sidlaw Hills and the Valley of Strathmore. 

 In a section of the country from the foot of the Grampians 

 in Forfarshire, to the sea at Arbroath, a distance of about 

 twenty miles, where the entire mass of strata is several 

 thousand feet thick, the triple division of the system is 

 very obvious ; namely, 1st, and uppermost, red and 

 mottled marls, cornstone, and sandstone. 2. Conglome- 

 rates, often of vast thickness. 3. Tiles and paving stones, 

 highly micaceous. The lowermost beds contain remains 

 of fucoid plants in abundance, f According to the 

 observations of Mr. Miller, each group is characterized 

 by the prevalence of a peculiar type of fishes (see ante, 

 p. 752). 



From the extension of the Devonian strata along the 

 northern shores of Scotland, numerous bays, friths, and 

 estuaries, have been produced by the long-continued action 

 of the sea, as is strikingly exemplified between Sutherland- 

 shire and Inverness.} " In a line of coast but little more 

 than forty miles in extent, there are four arms of the sea, 

 namely, the Friths of Cromarty, Beauly, and Dornoch, and 

 the Bay of Munlochy. The Frith of Tay, and the Basin of 

 Montrose, are also semi-marine valleys of the Old Red-sand- 

 three thousand feet in thickness have been removed." — Elements of 

 Geology, 2d edit. vol. i. p. 141. 



* Ibid. p. 23. + Ibid. vol. ii. p. 143. 



J " The county of Sutherland stretches across Scotland from the 

 German to the Atlantic Ocean, and presents throughout its whole 

 extent — except where a narrow strip of the Oolite formation runs along 

 its eastern coast — and an interrupted belt of Old Red-sandstone tips 

 its capes and promontories on the west a broken and tumultuous sea 

 of primary hills."— Mr 



