382 Correspondence. 
the same sections as those mentioned by Mr. E. Hull, of the Geo- 
logical Survey, but, on the contrary, are taken from a Brick-croft at 
a distance of about 300 yards, where nothing but Lower Boulder- 
clay is to be seen, with a covering of fine sand. The absence of the 
‘Laminated clays and bed of decomposed vegetation,’ in Section 
No. 1, that your correspondent gives, is owing to its being at a much 
lower elevation than Section No.2 that he speaks about, where he 
says that upon the surface (of what he calls Upper Boulder-clay) 
‘occurs a boggy soil, with branches of trees, some 3 feet thick.’ 
The difference that exists between the Upper Boulder-clay and the 
deposit at Heaton Mersey, to which he gives the same name, is so 
great that a novice would be able to see the distinction. The first is 
a hard, compact, and unstratified deposit, containing pebbles and 
striated boulders in abundance; whilst the second is a soft stratified 
or laminated deposit in which no pebbles nor boulders occur. An- 
other proof as to the difference of the deposit is well shown in the 
materials that are produced from them. The Boulder-clay is 
extensively used for brick-making, whilst the laminated clay is used 
for making earthenware. ‘The following is the section about mid- 
way from the top of Grundy Hill; it was taken yesterday :— 
Fine laminated sand . . 2 . 10 feet. 
Layer of peaty matter, about 3 feet thick, 
composed of decomposed vegetation, con- 
taining branches of hazel-trees, trunks, and 
roots, but not in an upright position . I foot. 
Dark-brown laminated clay, now known as 
‘warp’ . é : : : : . 3 feet: 
Lower Boulder-clay, varying in colour from 
red to bluish, containing striated boulders 
and remains of Bos primigenius : . 20 feet, and the 
base not seen. 
I may state, that I never before observed the trunks and roots of 
the hazel-trees in the bed that occurs on the surface of the ‘ warp,’ 
nor was I ever rewarded with finding the remains of Bos primi- 
genius in the Lower Boulder-clay of Heaton Mersey until my ex- 
cursion yesterday.— Yours, &c. J. WEBSTER KIRKHAM. 
Lowrr Broventon: May 5, 1865. 
To the Editor of the GEOLOGICAL MAGAZINE. 
DISCOVERY OF FOSSIL SHELLS IN THE SILURIAN SHALES OF 
DUMFRIESSHIRE. 
Srr,—The precise age of the Silurian beds of Dumfriesshire has 
always been a difficulty with Geologists, because the most diligent 
search has hitherto brought to light no higher organisms than 
Graptolites, with the exception of some very doubtful and obscure 
specimens—so obscure that the species could not be determined. 
It has been my good fortune to discover several specimens of 
shells in the Black Shales of Garpel Burn, which runs through a 
glen about 24 miles from the town of Moffat. I only found them 
after searching the shales on four consecutive days, spending a good 
