GARVH ISLAND, GEOLOGY. 511 



From the termination of the mass of limestone thus 

 described, to Loch Eribol, the whole space is occupied 

 by gneiss and quartz rock, the west side of that inlet 

 being entirely formed of the latter substance. The cal- 

 careous strata first appear in Eilan na Chorrie, situated 

 towards its upper end, and are afterwards found skirting a 

 portion of the eastern shore of the loch. 



This island is entirely formed of limestone, similar in 

 every respect to that already described, and maintaining 

 the same direction and dip. On the shore of the loch, 

 the sequence and contact of the adjoining rocks can 

 be traced in different points, so as to give the most 

 satisfactory evidence of their relations to the limestone 

 as it there occurs. From the southernmost point where 

 it is visible, to near Eribol house, the strata correspond 

 in dip with those of the island, proving that they are a 

 part of the same series, interrupted only by the sea. 

 In proceeding northwards along the shore, their elevation 

 increases, while the direction continues unaltered ; until, 

 at the point where the limestone finally terminates, they 

 occupy an angle of eighty degrees. The flexure neces- 

 sarily attending this change of elevation, is distinctly 

 visible, both in the limestone and in the accompanying 

 beds of quartz rock. 



From the relative dips of these rocks and that of the 

 gneiss which succeeds them, it might be readily deduced 

 that the limestone was inferior to the gneiss ; but a com- 

 plete series of demonstrative evidence on this subject, 

 can be obtained by tracing the eastern shore of Loch 

 Eribol from the upper extremity to the Whiten head. 

 The actual superposition of the quartz rock to the lime- 

 stone, and that of the gneiss to the former, may be 

 seen in various parts of the narrow tract that separates 

 this bay from Loch Hope. Where the limestone is about 

 to terminate, it is also found in actual alternation with 

 the quartz rock ; being here extenuated, and reduced 

 to two strata that are separated by one bed of this sub- 



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