Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/267



VIII. A Geological Description of Glen Tilt.

By, M.D. F.L.S. President of the Geological Society, Chemist to the Ordnance, and Lecturer on Chemistry at the Royal Military Academy at Woolwich.

Read Dec. 3, 1813, and the Supplementary Additions Dec. 16, 1815.

is well known that the appearance of the granite in various parts of the valley of the Tilt afforded to Dr. Hutton one of the original arguments on which his theory was founded. Hence this spot has acquired among geologists a sort of classical celebrity, sufficient to render it an object of interest, independently of that which is excited by the intricate and remarkable disposition of its rocks. Observations, now more numerous than in his day, have brought to light so many facts similar to those which appeared to him so important, that there is no difficulty in pointing out abundant instances of an occurrence once supposed rare. But having had occasion while examining these rocks to observe other interesting appearances, which have been either misapprehended or overlooked, I consider that a notice of them will not be unacceptable to the Society. The notice is accompanied by such specimens and drawings as are requisite for the illustration of the subject.

In describing Glen Tilt I have been under the necessity of differing on certain points from those who have preceded me. An examination of many of these points of difference would lead to discussions as endless as they would be fruitless, and give this