8 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 22, 



the cultivated patches of Heast the coast-line is fringed with sombre, 

 lichen-clothed crags of red sandstone and quartz-rock, stretching away 

 to north-east over a bleak moorland region, and swelling southwards 

 into the grey wrinkled mountains that form the long peninsula of Sleat. 

 Interior. — I have now gone over the coast-sections of the district, 

 whence a good idea may be gained of the general arrangement of the 

 rocks in the interior. To describe that arrangement regularly in 

 detail would be not a little tedious, and, from the want of local refer- 

 ences, would be attended with inconvenience and difficulty. I have 

 accordingly drawn several sections through the more remarkable 

 parts of Strath, whereby much is shown at a glance that could not 

 be so well understood even from the clearest description. These 

 sections, with the accompanying map, will, I trust, convey a fair 

 idea of the structure of the district. They show the Liassic region 

 of Strath to be a great synclinal trough bounded on the north-west 

 by syenite, and on the south-east and east by red sandstone, and 

 ridged up along its centre by an anticlinal axis. 



Notwithstanding this seemingly simple structure, there is not a 

 little complexity when we descend to details. Thus, we should ex- 

 pect that along the outer edges of the synclinal hollow, the lowest 

 beds would be always those visible, but this is not strictly true. The 

 most northerly of the sections, PL I. fig. 2, exhibits no sign of any 

 bending of the beds : these follow each other in regular sequence 

 from the lower conglomerate and coral-bed up to what is probably 

 the marlstone. Section III., MS., and fig. 5 display the full swell 

 of the anticlinal axis, and likewise the effects of denudation in 

 partly baring the sandstone-ridge of its mantle of limestone. The 

 lower beds seen at the eastern end of the line do not rise against the 

 syenite at the western ; those visible along the flanks of Beinn na 

 Cailleaich belong to a higher part of the series. The shales and 

 limestones at the foot of Ben Chro are not the bottom beds, nor do 

 these occur at the other edge of the trough on the shore of Loch 

 Eishort, for there, as shown above, the fault cuts off all the strata 

 below the white quartzite. And thus, though the general structure 

 of the district is that of a synclinal hollow, its regularity has been 

 assailed by syenite and faults. 



Nor is there greater regularity in the occurrence of the central 

 anticlinal ridge. Eastwards it is produced by a broad undulation 

 of the red sandstone and superincumbent lias without visible igneous 

 rock ; westwards it is caused by a long protrusion of syenite, while 

 midway there is a confused coalescing of the two axes. Moreover, 

 throughout nearly the whole extent of this cenlral area, the lime- 

 stones have been so altered that it is no easy task to ascertain their 

 true dip. They are ploughed up on all sides by trap-dykes ; faults 

 have dislocated their connexion; great protrusions of syenite have 

 ridged them up, and long tracts of red sandstone are found running 

 through their centre. 



Instead, therefore, of attempting to describe this confused district, 

 I must refer to the map and sections alluded to for the general dis- 

 position and relations of the rock-masses, and content myself with 



