672 



J. W. JUDD ON THE SECONDARY ROCKS OF SCOTLAND. 



very important degree, to the preservation of the fragments of 

 Mesozoic rocks. 



Thus in the case of the remarkable mass of Mesozoic rocks at 

 Applecross, though it is highly probable (alike from its proximity to 

 the Skye volcano and the fact of its being traversed by numerous 

 basaltic sheets and dykes) that this patch of strata was originally 

 buried under an accumulation of lava-sheets, which have since been 

 entirely removed by denudation, yet it is manifest that the great 

 faults which have clearly let down these strata many hundreds and 

 perhaps thousands of feet below their original level into the heart of 

 the mountains of Torridon Sandstone have had much to do with 

 their preservation (fig. 3). 



Fig. 3. — Plan and Section to illustrate the relation of the patch of 

 Liassic Strata at Applecross. 



a. Torridon Sandstone 



d. Lower Lias. 



The broken lines in the plan indicate the positions of the great faults. 

 The line X Y shows the line of the section represented below the plan. 



The action of great faults, in combination with a covering of sheets 

 of lava, in effecting the preservation of masses of Secondary strata 

 is very strikingly exhibited in the grandest of all the sections of 

 Mesozoic rocks in the Western Highlands, that of the eastern side of 

 the island of E-aasay, lying opposite to and only a few miles distant 

 from Applecross. This section is illustrated by the accompanying 

 diagram (fig. 2, p. 671), in which the'amount of disturbance to which 

 the strata have been subjected is strikingly apparent. 



The relations of the strata in the island of Scalpa, which I had 

 the opportunity of studying with one of the students of the School 

 of Mines, Mr. A. Grant, at the time resident in the island, are quite 

 similar to those just described in the island of Eaasay, the Middle- 

 Lias beds being thrown against the Torridon sandstone by a great 

 fault as shown in fig. 4. 



The most striking example, however, that can be adduced of the 

 action of faults in contributing to the preservation of the Secondary 



