30 Dr. Mac Cvllocu's Skelcb of ibe 



same siliceous enamel wliich is so remarkable at Balahulish. In 

 most situations it contains the common admixture of felspar in 

 grains. Although not, strictly speaking, stratified, it bears the 

 marks of having once been regularly so, the beds having been ren- 

 dered obscure, partly by the infinite number of cross fractures 

 which it has undergone, and partly by the bendings and displace- 

 ments which it has experienced. At Ord indeed some extent of it 

 is to be seen lying directly in contact with the beds of red sandstone 

 and in a conformable direction, and here the stratification is suffici- 

 ently regular to preclude all doubts, although the beds are not so 

 continuous and unbroken as those of the sandstone. 



But I must not quit this district without noticing a remarkable 

 circumstance, uncertain as I yet am whether the observation was 

 correctly made or not. If I have not an opportunity myself to 

 verify or contradict it, I shall at least point it out to those who may 

 follow me through this country. 



There is considerable intricacy as well as obscurity in the rocks 

 which I have now described on the western side of the Point of Sleat, 

 although on the eastern there is neither variety nor obscurity to 

 contend with, this intricacy arising partly from the frequent occur- 

 rence of insulated portions of the secondary strata skirting the 

 shores, and of which the further details are cut off by the irregular 

 indentation of the sea line. Thus they become in a ropographical 

 sense intermingled with the micaceous schist and with the quartz 

 rock in a very irregular manner, while the general confusion is 

 much augmented by the great number and perseverance of the trap 

 veins which traverse them. It is extremely difficult to find a way 

 through this geological labyrinth. It is near Gillan, where among 

 other places this confusion occurs, that the phenomenon in ques- 

 tion is to be seen : a bed of highly compact grey limestone contain- 



