Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/190

 tending to remove. Repeated and careful examination of them as they occur in the western islands, have, since the time at which the original paper on Sky was drawn up, enabled me considerably to amend their history, and to dispose of them in a more exact and connected manner; but as the detail would here be inadmissible, from the length of discussion to which it would lead, I shall make no attempt to improve the former imperfect remarks, but reserve that which might be here added, for some future communication. I shall however attempt to amend one or two of the descriptions contained in the former paper, where I had been obliged to rely on a distant view, and was therefore compelled to speak only in the most general terms.

The first of these portions of trap is that which occupies the district of Trotternish, of which, as well as of the stratified substances but just described, I had formerly an opportunity of forming only a very superficial notion.

As I have just shewn, it both intersects and surmounts the secondary strata, while in many places it appears also to be horizontally or conformably interstratified with them. These interferences are very remarkable, and exhibited on a scale of such extent as to include every circumstance which has yet been described on the subject of their junctions. But without numerous drawings no adequate idea of them can be conveyed, and as there is little to be said respecting them which would not be a repetition of the remarks which have on numerous occasions been made on similar appearances, I shall forbear to enter into details respecting them. I shall only observe, that all these irregularities occur in a stratified, which taken in a general view, has the character of a stratified trap, since notwithstanding them it bears a strong parallelism to the already parallel strata with which it is associated. It is abundantly