Several thousand years ago, ere the upheaval of the last of our raised beaches, there existed somewhere on the British coast a submarine bed, rich in sea-weed and the less destructible zoophytes, and inhabited by the commoner crustaceæ and molluscs. Shoals of herrings frequented it every autumn, haunted by their usual enemies the dog-fish, the cod, and the porpoise; and, during the other seasons of the year, it was swum over by the ling, the hake, and the turbot. A considerable stream, that traversed a wide extent of marshy country, waving with flags and reeds, and in which the frog and the newt bred by millions, entered the sea a few hundred yards away, and bore down, when in flood, its modicum of reptilian remains, some of which, sinking over the submarine bed, found a lodgment at the bottom. Portions of reeds and flags were also occasionally entombed, with now and then boughs of the pine and juniper, swept from the higher grounds. Through frequent depositions of earthy matter brought down by the streamlet, and of sand thrown up by the sea, a gradual elevation of the bottom went on, till at length the deep-sea bed came to exist as a shallow bank, over which birds of the wader family stalked mid-leg deep when plying for food; and on one occasion a small porpoise, losing his way, and getting entangled amid its shoals, perished on it, and left his carcase to be covered up by its mud and silt.