420 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [JuHG 16, 



in these beds. The roots of the trees in the bed e are often fixed in 

 the red clay below, in which they appear to have grown. The upper 

 beds exhibit more of a lacustrine or fluviatile character, and near the 

 high grounds become more arenaceous and gravelly than in the central 

 parts of the valley. They thus indicate the margin of the ancient lake 

 in which these strata were probably deposited. The whole formation 

 reminded me of the freshwater and lignite beds on the north-east 

 coast of Norfolk, formerly described by Sir Charles Lyell, and may 

 probably be regarded as of nearly the same age. It is evidently more 

 recent than the red Boulder Clay or Till, but also clearly older than 

 the great peat-bed now forming the surface of the district. The 

 upper beds were probably deposited in a shallow lake which may 

 have been drained by the river cutting down the bank of sand and 

 gravel by which the water was retained, in consequence of its increased 

 action when the land was raised. 



The section fig. 6, seen in the bank of the small river near Ma- 

 Fig. 6. — Section near the mouth of the Machrihanish River. 



inches. 



a. Soil and blown sand 10 to 12 



h. Round water-worn gravel 18 



c. Peaty soil with remains of plants 10 



d. Brown arenaceous clay 



e. Sandy clays with layers of gravel 

 /. Beds of sand and gravel 



inches. 



30 



36 to 48 



chrihanish, exhibits the relation of these older and lacustrine beds to 

 the blown sand and more recent deposits on the coast. The whole 

 shore of the bay is occupied by hills of blown sand, covered by scanty 

 herbage. In this place these blown sands are seen resting uncon- 

 formably against the ends of the more ancient beds, and, what is 

 curious enough, the newer beds are inclined at a considerable angle, 

 whilst the older ones are nearly horizontal. 



That the shores of the Firth of Clyde have recently been elevated 

 about 30 feet above the former level of the sea is now so well known, 



