Page:Cornwall; Cambridge county geographies.djvu/68

 52 CORNWALL the English Channel, the other being the Severn. At that time the Bristol Channel was another great valley. From Brown Willy to the Scilly Isles ran a lofty mountain range, towering into the sky, of which the present Bodmin moors, Carn Brea, Carn Marth, Tregonning Hill, etc., are but the abraded stumps. Not only were they much higher, but their present roots stood 300 ft. higher than at present. Then ensued a sinking of the land, and the Atlantic flowed into the valley to the south and joined the North Sea; and at the same time the Bristol Channel was formed. Thus the present coast was approximately outlined. At some period shortly after, a vast inundation swept over the land from the north, and carried down the degraded granite, depositing the tin beds in the hollows. As early as 1830, Mr Came noted: "The peculiar situation in which nearly all the stream tin of Cornwall is found is highly illustrative of the direction in which the current of the deluge swept over the surface. All the productive streams are in the valleys which open to the sea on the southern side of the Cornish peninsula; whilst most of the richest veins are situated near the northern coast." The deposit of tin stone, or tin ground, lies directly on the shel^ or primitive surface of rock, and is carried far out in the estuaries, and overlaid by marine deposits. In 1828, in Carnon Creek, a cairn was discovered 1 6 to 1 8 ft. below the surface, and that surface 4 to 5 ft. below low water mark. In it was a crouched skeleton. This shows that there must have been a subsidence of the