1873.] CAMPBELL — GLACIAL PHENOMENA OF THE HEBBIDES. 545 



sistibly to the conclusion that the great ice-sheet did not stay its 

 onward march until it reached the edge of the 100-fathom plateau, 

 some 45 or 50 miles beyond the Outer Hebrides, and calved its ice- 

 bergs in the deep waters of the Atlantic. 



Discussion.* 



Prof. Owen corroborated the author's views as to the grand marks 

 of glaciation on the island of Lewis, which had conio under his per- 

 sonal observation. 



5. Notes on the Glacial Phenomena of the Hebrides. 

 By J. P. Campbell, Esq., P.G.S. 



As I shall be unable to be present at the reading of Mr. Geikie's 

 paper on the Glaciation of the Outer Hebrides, I beg to submit to 

 the Geological Society some extracts from my journals containing 

 observations on the glacial phenomena presented by the western 

 islands. 



Tiree, Sept. 1871. — The island is flat ; and the low grounds appear 

 to have been under water. The highest hill is Heynish, at the 

 south-west end, and 500 feet high. On the top of the hill are a 

 great many large perched blocks ; some are 14 or 15 feet long. So 

 far as I could make out, they came from the north-west ; they are 

 chiefly gneiss, like rocks in the outer islands. The rocks are gla- 

 ciated and weathered. 



.Harris, Sept. 17. — The hills are made of contorted Laurentian 

 gneiss, and much glaciated, but weathered. So far as I could make 

 out, the ice came from N.N.W. through a gorge at Tarbet. 



Bernevay to Barra. — Bernevay is the last of the Hebrides ; the 

 whole chain looks like the hill-tops of a drowned continent. The sepa- 

 rate islands are rocky and grassy, and are about 1000 feet high or less. 

 On the east side these hills slope down to the Minch. On the west 

 the Atlantic has battered the hills, and broken them, so that 

 great cliffs now plunge sheer down, or overhang the sea. Where 

 the rock is soft, the Atlantic waves dig into it, and make sea-caves, 

 and there work mischief till the roof comes down. Then a rift 

 cuts eastwards into the mountain, and becomes a " gha," in which the 

 sea-birds abide. The structure of the rock is seen in these great 

 cliffs as in a geological model ; and the way in which the surface- 

 forms are carved out of the solid is as plainly seen as in the grain 

 of a wood-carving. Whatever denuding engine was the most effi- 

 cient here, certain it is that ice had a great deal to do with this 



* A telegram was received from Dr. Bryce on the day of the Meeting, which, 

 owing to a misunderstanding as to its object, was not read at the Meeting. It 

 was to the effect that Dr. Bryce bad satisfied himself from observations made in 

 Lewis, Harris, and North Uist, and had published his opinion last year, that 

 the ice which produced the glacial markings in those islands had come from a 

 land to the westward, since submerged. This view nearly coincides with that 

 advocated by Mr. J. F. Campbell in the following paper. 



