WEST CUMBERLAND AND NORTH LANCASHIRE. 



37 



have the same compact nature, and, so far as I havo been able to 

 ascertain, contain the same kind of plants. 



3. Deductions. 



So little was known of the extent of the Lindal deposit at the time 

 Mr. Bolton and Miss Hodgson wrote, that its real geological import- 

 ance was missed. "We now see that it is overlain by an immense 

 mass of Boulder-clay, in some places nearly 100 feet thick ; it is 

 also underlain by Boulder-clay ; so that I think we may fairly say it 

 is interglacial. The impossibility of its being a recent introduction, 

 carried down by means of swallow-holes, as suggested by Miss 

 Hodgson, must be apparent to every one now that we know more 

 of its extent and real nature. 



We may ascribe a like (that is, interglacial) age to the deposits 

 at Crossgates. The deposits in solid rock were, I believe, thrown 

 down in preexisting cavities in the Limestone at the same time as 

 the deposits immediately below the Boulder-clay. 



The shore-deposits, so-called submerged forests, I think are also 

 of the same age. We are not able to prove it so directly as in the 

 case of the other deposits ; but I think that a careful consideration of 

 all the facts must lead any one to the conclusion that they are 

 interglacial. The fact upon which I most rely is their compact 

 nature, which, to me, speaks most forcibly of their having been 

 subjected to great pressure, such as would be the case if they had 

 been overlain by the upper glacial beds. They are altogether unlike 

 the spongy peat which occurs in St.-Bees valley, and quite as unlike 

 any of the vegetable deposit s which usually go by the name of peat, 

 although many of the species of plants found in the shore-deposits are 

 common to peaty accumulations. 



These shore-deposits all rest on the Lower Boulder-clay, a fact 

 which is somewhat remarkable if they are of postglacial age. Why 

 should we not find some of them on the Upper Boulder-clay ? 

 Besides, how can it be for a moment doubted that the Walney 

 deposit extends below the Boulder-clay, although this has not been 

 directly proved. .Referring to Plate III. figs. 6 & 7, we see that the 

 deposit dips towards the land, and that it is only about 50 feet from 

 high-water mark, where we have the Upper Boulder-clay. When to 

 these facts we add that the shore is travelling rapidly inland, it seems 

 to me we are bound to admit the Interglacial age of the deposit. 



Usually these deposits on the sea-shore pass by the name of 

 " submerged forests but the conclusion to which I am led is, as 

 already stated, that they are not forests at all, nor the sites of 

 forests, but that the vegetable matter has been accumulated under 

 water. All the facts but one point in this "direction : the Diatoms, 

 the rush-like stems and leaves (probably of a species of Sparganium), 

 and the interbedded layers of sand, all speak of watery conditions ; 

 the only fact which seems to me to indicate in any way that these 

 deposits are the remains of ancient forests that grew on the spot, is 

 the occurrence in them of a few root-stocks in their normal position. 



