Lias and Oolites of Scotland. 199 



afc Dunrobin, and the younger at and near Helmsdale 

 A great fault, nearly 20 miles in length, runs along the 

 shore, and throws the secondary strata down against the 

 older Palaeozoic rocks on the north-west. Interstrati- 

 fied with the black shales near Helmsdale, there are 

 occasional beds of brecciated conglomerate. The shales 

 contain thin layers of plants and many broken shells, 

 and the breccias contain angular and subangular 

 blocks, chiefly of Old Red Sandstone, with a mixture of 

 the older rocks of the Highlands, sometimes 6 or 8 feet 

 in diameter, in fact, boulder beds, which long ago 

 suggested to me the action of floating ice. Mr. Judd 

 suggests that they may be due to river ice, floated on 

 streams flowing from the west, at a time when the larger 

 part of the gneiss of the Highlands was covered by Old 

 Red Sandstone, since denuded. 



In the Inner Hebrides, the Lias, Inferior Oolite, 

 Middle Oolite and Oxford Clay occur in the Island of 

 Skye. The Lias, as described by Geikie, consists of beds 

 of limestone, sandstone, conglomerate, and shale. It 

 contains the usual fossils. The rocks are much dis- 

 turbed, and the limestones have been metamorphosed 

 into crystalline marble accompanied by the intrusion of 

 syenite. The section at Loch Staffin, given by Edward 

 Forbes, is as follows: 



Oxford Clay. Inferior Oolite. 



Estuary Shales. Lias. 



Middle Oolite. 



Between the Middle Oolite and estuary shales, a bed 

 of columnar basalt is intercalated, and the whole is 

 overlaid by amygdaloidal trap, which breaks through 

 and overspreads the strata. These igneous rocks are 

 intrusive and of Miocene age. The estuary shales con- 

 tain Oysters, Unios, Cyrenas, Paludinas, &c., distinct 



