GEOLOGICAL LETTERS AND NOTES 281 



sterile county, and lies immediately under the Secondary Sandstone, 

 as may be seen at Dnnnet Head and the Bay of Thurso and along 

 the coast Southward, and insensibly grades into the Old Red Sandstone, 

 assuming a redder colour and thicker beds as it approaches it, until 

 it becomes a regular conglomerate. The mineral pitch also belongs 

 to the clay Slate. Its discovery has induced several unsuccessful 

 attempts to find coal. The Slate promises to be of more value, as it 

 rises (in a quarry on the shore of the Bay of Thurso) in flags of 

 10 to 12 feet square and of an inch in thickness, is very strong and 

 durable, and resists water. It makes capital flooring, may be sawn 

 into tables, shelves for pantries, and takes a good polish. It is 

 coming into use in ornamental buildings, for a single slate will roof 

 a turret, and may be built into the walls. Fourteen cargoes were 

 shipped this season by Mr Trail, principally I believe for the 

 Edinburgh market. 



I think I shall be able to send, or personally deliver, my papers 

 and maps in a month or six weeks. I remain, etc. 



Matthew Culley. 

 P.S. — I have Parkinson's Org. Remains. Pray what are the 

 best publications on fossils?" 



In May of this year Mr Murchison started on a journey 

 to the North of Scotland, and writing, en route, to Mr Culley, 

 proposed to visit him at Coupland Castle : — 



Hazelbeach, Northampton, 28th May, 1826. 



"I beg to return you many thanks for your obliging letter 

 relating to the geology of Sutherland and Caithness, the substance 

 of which I communicated to the President and several leading 

 persons in the Society. Prom the interest which your specimens 

 of fossils from Brora excited in my mind, I had resolved (prev- 

 ious to the receipt of your letter) to undertake an expedition to 

 that district this summer, having been encouraged to do so by 

 many eminent workmen in our science, among others by Dr. 

 Buckland and Mr Lyall, my predecessor in the office of Secretary. 

 These gentlemen visited the Brora coalfield in their Highland 

 excursion, and altho' they brought away many specimens — a 

 section of the colliery and many particulars, yet they felt them- 

 selves unable to publish any decisive account of the exact 

 geological relations of that coalfield, from want of time and 

 leism-e when upon the spot. 



It was my full intention to have examined in detail the coalfields 

 of the Yorkshire Eastern moorlands previous to my survey of 

 the Brora field, but owing to the General Election in England, 



