312 SKY. GEOLOGY. RED SANDSTONE, 



of quartz or sandstone, and of schist, amount each 

 to a few inches only in thickness; while the appearance 

 produced in the sections, partly by this cause and partly 

 by the contortions, is such, that in approaching to exa- 

 mine the rocks by the hammer we feel perfect confidence 

 that we have at length arrived at the gneiss which we 

 have so long been seeking. 



The only change however to be traced is the more 

 constant induration of the quartz, which becomes gra- 

 dually crystalline, containing imbedded grains of red 

 felspar, the schist however undergoing no corresponding 

 change. But at length this substance acquires a greenish 

 hue, while the felspar assumes a laminar disposition. 

 Thus by degrees the rock passes into chlorite schist, inter- 

 laminated with felspar and containing sometimes talc and 

 mica ; while at length, arriving at the eastern point of 

 Sleat, we gradually return to the modifications of 

 gneiss formerly described, without having determined 

 a point at which the one series ended and the other 

 commenced ; the direction and general dip having all 

 along remained constant while the substances were 

 changing. I may remark in terminating this account 

 that the contortions last described are unconnected with 

 trap veins ; since, although these occur even as far as the 

 point of Sleat, they cease to be numerous or remarkable.* 



From the preceding facts, which have been detailed 

 with a minuteness justifiable only by their novelty and 

 importance, it appears, that there is in Sky a series of 



* It will be remembered that, in describing the eastern shore of Lewis 

 and that of North Uist, the transition of gneiss into an argillaceous schist 

 was pointed out. There is a considerable analogy in those cases and 

 the present one; and it is not improbable that if we could gain access to 

 the continuation of that schist, from which we are excluded by the sea, 

 we should find it to be part of a series analogous to that of Sky and 

 connected with a similar series of sandstone. Additional instances in 

 support of this opinion occur in many ports of the adjoining mainland, 

 at Loch Carron, in Glen Elg, Kintail, and Sutherland, where similar 

 transitions to schist and to red sandstone may be observed. 



