134 Bed of fossil Shells on the Banks of the Forth. [Aug. 



gow, and stretches along the hanks of the frith of Forth into Stir- 

 lingshire. 



The shells which are found in this bed are all of them inhabi- 

 tants of the sea, and still exist in a living state. The common 

 oyster occurs in the greatest abundance, and occupies more than 

 three fourths of the bed. The common muscle may also be ob- 

 served, but in small quantity. The following shells occur more 

 sparingly: patella vulgaris, buccinum undatum and lapilhcs, turbo 

 littoreus, nerila lit (oralis, and Venus pullastra. There is little sand 

 or clay mixed with these shells, so that the bed is very open in its 

 structure. In the cavil ies formed by the shells resting upon one 

 another I observed the remains of several land shells. But a very 

 superficial examination convinced me that these were to be con- 

 side; ed as foreign to the bed. In search of nourishment and shelter, 

 many specimens of helix lucida, rujiscens. nemoralis and radiata, 

 were, at the time I examined the bed, crawling among the marine 

 shells, and dead specimens of these were very common in the 

 cavities. 



Many of the shells contained in this bed are of a very large size, 

 and must have belonged to very aged individuals. Among the 

 bivalved shells, there are a few perfect specimens, having the valves 

 still in contact. But in general the valves are detached, and the 

 shells broken into moderately sized fragments, so that the bed pre- 

 sents an appearance of confusion. The shells themselves are a little 

 altered in their texture. Thev are soft and friable, occasioned by 

 the decomposition of the animal portion of their constitution. The 

 epidermic is completely destroyed, together with the ligaments. 



'lids lied appears to vary in thickness. Towards its eastern 

 c rr'emitv. where it is distinctly seen, it is upwards of three feet. 

 It here rests on a bed of small gravel, and is covered with clay and 

 soil. ;? preserves in all the parts of its course nearly the same 

 eleyation above the surface of the river. In one place 1 ascertained 

 its height to he 83 feet above high water mark. 



The . \t' nt of this bed is very remarkable. It makes its appcar- 

 a ce al (-•it iwo milps to the westward of the town of Borrotvstoun- 

 m^s, al .i plai e called Craigehbuck. Here a limestone quarry has 

 been Q| ened, and the excavation in the face of the bank has 

 exposed ti> view ;> very distinct section of the bed. This appears to 

 he its eastern extremity. It extends in a westerly direction along 

 the big!', bank on the' south side of the road, and may lie distinctly 

 seen at In Vera von. It ha- also been observed in the neighbourhood 

 of Linlt therse, and to the westward of the village of Polmont, in 

 Stirlingshire. It thus extends in a line parallel with the banks oi 

 the !-oii|) upwards of three miles. Between this high bank, in 

 whit I 'he bed of shells occurs, and the shore of the Forth, there is 

 an exteusive deposition of alluvial soii called carse ground, nearly a 

 mile in breadth, and at present in a high state of cultivation. 



TJie shell? contained in this bed are common in the frith in a live 

 state, but at present we are not acquainted with any beds of oysters 



