HKB
of Loch Fyne, Loch Awe, and the magnificent hoary-headed Ben Cruachan, requiring a base of more than twenty miles to support him,--besides the beautiful and majestic scenery of the neighbourhood.
But my chief interest was in the specimens of high geological interest which the Duke showed me. He had discovered them in the Island of Mull, in a bed of clay shale, under a volcanic basaltic cliff over eighty feet high, facing the Atlantic Ocean. He found in this bed many beautifully perfect impressions of forest tree leaves, chiefly of the plane-tree class. They appeared to have been enveloped in the muddy bottom of a lake, which had been sealed up by the belching forth from the bowels of the earth of molten volcanic basaltic lava, and which indeed formed the chief material of the Island of Mull. This basaltic cliff now fronts the Atlantic, and resists its waves like a rock of iron. To see all the delicate veins and stalklets, and exact forms of what had once been the green fresh foliage of a remotely primeval forest, thus brought to light again, as preserved in their clay envelope, after they had lain for ages and ages under what must have been the molten outburst of some tremendous volcanic discharge, and which now formed the rock-bound coast of Mull, filled one's mind with an idea of the inconceivable length of time that must have passed since the production of these Wonderful geological phenomena.
I felt all the more special interest in these specimens, as I had many years before, on my return visit from Londonderry, availed myself of the nearness of the Giant's Causeway to make a careful examination of the marvellous volcanic columns in that neighbourhood. Having scrambled up to a great height, I found a thick band of hematitic clay underneath the upper bed of basalt, which was about sixty feet thick. In this clay I detected a rich deposit of completely charred branches of what had once been a forest tree. The bed had been burst through by the outburst of molten basalt, and converted the branches into charcoal. I dug out some of the specimens, and afterwards distributed them amongst my geological friends. The Duke was interested by my account, which so clearly confirmed his own discovery. On a subsequent occasion I revisited the Giant's Causeway in company with my dear wife. I again scrambled up to the hematitic bed of clay under the basaltic cliff, and dug out a sufficient quantity of the charred branches, which I sent to the Duke, in confirmation of his theory as to the origin of the leaf-beds at Mull.* [footnote...
I received the following reply from the Duke of Argyll dated "Inverary, Nov. 19, 1850": --
"MY DEAR SIR--Am I right in concluding, from the description which; you were so kind as to send to me, that the lignite bed, with its superincumbent basalts, lies above those particular columnar basalts which form the far-famed Giant's Causeway? I see from your sketch that basalts of great thickness, and in some views beautifully columnar, do underlie the lignite bed; but I am not quite sure that these columnar basalts are those precisely which are called the Causeway. I had never heard before that the Giant's Causeway rested on chalk, which all the basalts in your sketch do.
[Image] The Astrologers Tower--A Day Dream. By James Nasmyth. (Facsimile.)
"I have been showing your drawing of 'Udolpho Castle' and 'The Astrologer's Tower' to the Duchess of Sutherland, who is enchanted with the beauty of the architectural details, and wishes she had seen them before Dunrobin was finished; for hints might have been taken from bits of your work. --Very truly yours,
ARGYLL." ...]