38 MR STEVENSON ON THE GEOLOGY OF COCKBURNLAW, 
3. The Coal Measures. 
This important formation is represented in this district, by a small patch 
east of the Cumledge trap-dyke. Its strata are well exposed in the bed of the 
Whiteadder, near Preston bridge, about a quarter of a mile below which, are two 
fine sections. There the sandstones, shales and clays, which characterize the for- 
mation, are seen dipping away from the dyke at high angles, and presenting the 
usual appearances by which this series of strata is elsewhere distinguished. The 
shales and clays contain a large proportion of carbonate of lime in their composi- 
tion; so much, indeed, that they might almost be termed limestones. The sand- 
stones are of the usual white or yellowish colour, in many places highly micaceous. 
and abounding in impressions of Stigmariz, Sigillarize, Lepidodendra, and other 
plants of the carboniferous system. There is no appearance of animal remains.* 
No coal seams appear, but there is a thin stratum of ironstone in nodules, which 
abounds in remains of plants. The geological position of these strata, and the 
other rocks of the same formation, which prevail in the Merse of Berwickshire is 
considerably below the Encrinal limestone, which crops out near Berwick, and on 
the sea-shore at Lamberton. Indeed, they properly belong to the mountain lime- 
stone series, being situated far below the true coal measures. From their very 
low position in the series, there is no reason to suspect the existence among the 
Berwickshire strata of any coal-seams sufficiently thick to be worth working. 
II. Igneous Rocks oF THE DISTRICT, AND THEIR EFFECTS UPON THE SEDIMENTARY 
Rocks. 
Throughout the district under consideration, trap-rocks are very abundantly 
distributed, and present a field of speculation, no less attractive than those of 
aqueous origin. The traps of the Lammermuirs and adjoining districts belong to 
two great classes, differing from each other, as well in mineral character and 
general aspect, as in regard to the epochs of their eruption. These are the Por- 
phyries and Greenstones, or Felspathic and Augitic traps, both of which classes are 
very abundant, but (with one or two exceptions, to which we shall afterwards 
have occasion more particularly to refer) do not occur associated with each other; 
for it is a remarkable fact, that while the traps which occur among the greywacke 
of the hills are uniformly of the Felspathic class, those which appear in connection 
* Within the last few weeks the remains of fossil fishes have been discovered in the course of 
Langton Burn, about a mile SW. from Dunse, in strata belonging to the lower part of the coal mea- 
sures. These remains consist of scales, spines, teeth, and other bones, similar to those found at Burdie- 
house. They occur ina soft friable sandstone, which abounds also in Lepidodendra, and other plants 
of the coal formation. Some remains of the Holoptychius have likewise been recently found in the old 
red sandstone strata on the estate of Billie, about four miles NE. from Dunse.—21st April 1845. 
