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GEOLOGT OF BUTE. 



131. A PRETTY full and generally accurate account of the 

 Geology of Bute has been given by Dr. MacCulloch in his 

 work on the Western Isles, published in 1819. For thirty 

 years after, no observations, so far as we can learn, were 

 put on record respecting it, except some notices of its 

 remarkable coast terrace and raised shelly deposits, by Mr. 

 Smith of Jordanhill. The greater variety of the strata in 

 Arran, and the bearing of the phenomena there exhibited 

 upon questions in theoretical geology actively discussed at 

 the time, drew attention entirely to that island; and Bute, 

 in common with other parts of the west of Scotland, was 

 overlooked. Yet it has many points of great interest; 

 strata occur here to be m et with nowhere else in Scotland, 

 and the effects of its trap dikes upon the adjoining strata are 

 extremely curious indeed, of a unique character. 



Physical Features. 



132. Three deep depressions or valleys traverse Bute 

 perpendicularly to its longer axis, dividing the island into 

 four portions, and marking the boundaries of distinct 

 geological formations. They terminate on either side in 

 bays or indentations of the land, formed here, as in most 

 other cases, at the points of least resistance, the junc- 

 tions, namely, of dissimilar strata. Those on the east side 

 are the well-known sheltered bays of Kames, Rothesay, and 

 Kilchattan. The low tracts in question shew no rock in 

 situ, but are filled with shingle and alluvial deposits conceal- 

 ing the junctions, strata of peat, and occasional shell-beds. 

 The elevation above the sea level nowhere exceeds 30 feet ; 

 and as this is also very nearly the height of the terrace 



