96 REPORT—1858. 
in the lower and redp ortions of the deposit, and also occurs in the overlying yellow 
sandstones, associated with other old red ichthyolites, the age of the deposit is clearly 
substantiated. 
In conclusion, Sir Roderick said that this communication must be considered as a 
rehearsal only of what he hoped would be done with more effect next year at Aberdeen, 
when further observations might lead hin: either to confirm or modify that portion 
of his views which relates to the age of the Elgin sandstones. In the mean time, the 
fundamental reform of the North Scottish series is above narrated, proving that the 
ascent from rocks on the west coast, which are unquestionably older than any in 
England and Wales, through Cambrian and Lower Silurian rocks to the much 
younger ‘‘ Old Red Sandstone” of the east coast, is firmly established. ‘The commu-~ 
nication was illustrated by several geological maps, to indicate the successive steps in 
knowledge, including an old one coloured by himself thirty-one years ago, the maps 
of M‘Culloch, Nicol, and Knipe, and a map of Sutherland, which the author had 
coloured during the summer. Besides large diagrams, there were sketches of the 
mountains and lochs of the west of Sutherland by Miss Charlotte Dempster. 
On the Age and Relations of the Geiss Rocks in the North of Scotland. 
By James NIcou, F.RS.E., F.GS., Professor of Natural History in the 
University of Aberdeen. 
The author expressed his regret that in one point he was compelled to differ from 
his distinguished friend Sir R. I. Murchison. He could not regard the entire gneiss 
forming the central regions of Ross and Sutherland as of younger age than the red 
sandstone and quartzite of the west coast (Cambrian and Silurian of Murchison). He 
described a section from the Gairloch to the Moray Frith, and showed that the red 
sandstone and quartzite resting on the gneiss of the west, were cut off by a mass 
of felspar-porphyry and serpentine from the supposed overlying rocks on the east. 
He had traced a band of similar igneous rocks at intervals for a hundred miles, from 
Loch Eriboll to Skye, and had observed other indications of fracture and convulsion 
along this line, as shown in the section exhibited. He therefore concluded that the 
overlap of gneiss on quartzite might be occasioned by a slip or convolution of the 
strata, and not mark the true order of superposition. He also stated, that the uncon- 
formability of the quartzite tu the red sandstone (Cambrian) which he had described 
at Assynt and on Loch Broom, did not seem to occur in Gairloch, where the two 
deposits, as seen in great sections on the escarpments of the mountains, appear quite 
conformable; the red sandstone, however, extending far beyond the quartzite on the 
west. He further pointed out, that, in the central region of Scotland, from Aberdeen- 
shire to Argyllshire, the great formation of gneiss, with limestone and quartz rock, 
overlies the mica slate, and does not dip under it, as usually represented. In parti- 
cular, the gneiss of the Black Mount and Breadalbane Highlands appears to form a 
wide synclinal trough resting ou both sides on mica slate, and thus to be an overlying 
and younger formation. 
On the Comparative Geology of Hotham, near South Cave, Yorkshire. 
By the Rev. T. W. Norwoon, of Cheltenham. 
The village of Hotham is upon the lower lias; but all the secondary rocks of this 
part of Yorkshire, from the new red sandstone to the chalk inclusive, may be seen in 
its immediate neighbourhood. Their course is nearly N.N.W. At Hotham proper 
we are only concerned with the lias and inferior oolite; to them therefore these 
remarks are limited. 
I. Between North Cave and South Cliff the lower lias “limestones and shales” pre- 
sent to the plain their usual elevated outcrop, and exhibit plentifully their charac 
teristic fossilsk—Gryphea incurva, Lima gigantea, Ostrea liassica, Modiola minima, 
and many other familiar forms. ‘The ‘“ Bone-bed”’ and “ Insect-bed” appear to be 
wanting. The lias passes conformably, and somewhat suddenly, into the sandy beds 
below it. 
A great destruction has happened to the lower lias in this locality, The north side 
