114 MR. CLEMENT EEID ON A PROBAHLE [May I 904, 



Ludgvan. An excellent description of these deposits was given, as 

 long ago as 1758, by William Borlase, the Cornish geologist, who 

 was rector of the parish in which they are found. His account is 

 as follows : — 



'It has been generally held by Naturalists that we have no flints native in 

 Cornwall, but this is a mistake. Betwixt the towns of Penzance and Marazion 

 there is a beach of pebbles two miles and three quarters long, among which 

 many hundred flints may be picked up every day ; and lest it should be in- 

 sinuated that these flints may possibly be foreign, and brought in ballast by 

 ships, I must observe, that in the low-lands of the parish of Ludgvan, scarce a 

 musket-shot from the said beach, in a place called the Vorlas, there is a 

 stratum of clay about three feet under the grass : the clay is about four feet 

 deep. In this clay, immersed from one to four feet deep (sometimes deeper) 

 flints are discovered in great numbers, their size from the bigness of a man's 

 fist to that of a bean, their coat nearly of the colour of the clay, (as in chalk 

 we find tbeir exteriour infected with the chalk-bed in which they lie) and their 

 inward part died with the same colour more than half way ; the other part, 

 near the middle, a common, corneous, brown flint. In the same bed of clay, I 

 find sea-pebbles of opake white quartz, and some shingle ; sufficient and evident 

 vestiges of the universal deluge. I find also many small blue killas stones, 

 with all their angles on ... . The flints of this bed of clay are brown within, 

 but on the beach we have a remarkable variety, and one now before me of an 

 opake white, is of as fine texture, and as high a polish, as any Carnelion I have 

 ever seen ' [probably the chalcedonic Greensand-chert of Ha Id on]. 1 



The gravel is still dug at the place that Borlase names : it occurs, 

 as Borlase pointed out, away from the sea and above the sea-level 

 (usually 20 or 30 feet above), therefore it cannot be accounted for 

 by any transportation as ballast. Though the name ' the Vorlas ' 

 is now forgotten, the old gravel- pits will be found on the landward 

 side of Marazion marsh. In the small pits now open the flints 

 are subangular, often up to 2 or 3 pounds in weight, and are mixed 

 with Greensand-chert and a considerable amount of the local 

 Pala?ozoic material, in a matrix of sandy loam. The origin of this 

 loam, which is certainly not the original matrix, I do not propose 

 here to discuss : it probably forms part of the raised beach which 

 fringes Mount's Bay ; but the sections now seen are scarcely satis- 

 factory. It only concerns us here to point out that the large 

 quantity of flint-gravel is not ballast, but was apparently there 

 before the land was inhabited. 



Certain striking characteristics of these flints seem not to have 

 attracted the attention that they deserve. Though so far from 

 any exposure of Cretaceous rock, they are subangular ; and they 

 are weathered and ' annealed ' in the same curious way that is seen 

 in the flints of the Eocene gravels of Devon and Dorset. In fact, 

 the resemblance of the material to that of Haldon is so striking, 

 that I feel sure that both flint and chert are derived, not directly 

 from Cretaceous rocks, but through the intermediary of some 

 Eocene river-gravel, such as was described iu the two papers 

 already published. 



So far as we know, there is no reason to suppose that any Eocene 

 outlier still exists in the county ; but the curious localization of an 



i t 



Natural History of Cornwall ' folio, 1753, p. 106. 



