Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/38

From Wikisource
Jump to navigation Jump to search
This page has been proofread, but needs to be validated.


same siliceous enamel which 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 rendered obscure, partly by the infinite number of cross fractures which it has undergone, and partly by the bendings and displacements 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 sufficiently 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 occurrence 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 topographical 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 question is to be seen: a bed of highly compact grey limestone containing