THE CONSTITUENTS OF A SEABEACH 59 



here the old shell-banks and sand-banks known nowa- 

 days as "the Red and Coralline Crags," the London 

 clay cliffs and clay sea bottom were in existence just as 

 they are now. But in that period there existed here 

 enormous quantities of bones of whales of kinds now 

 extinct, which had lived a little earlier in the sea of this 

 area, and were deposited in vast quantity as a sort of 

 first layer of beach or shallow water sea-drift. Bones 

 consist largely of phosphate of lime, and are used as 

 manure. In that old crag sea the phosphate of lime 

 was dissolved from the. deposit of bones, and as we find 

 occurring in the case of other clays and other bones 

 elsewhere — was chemically taken up by the clay — the 

 same kind of clay which to-day is being converted into 

 " cement-stone." It was thus, at that remote period, 

 converted into " clay phosphorite," owing to the presence 

 of the immense deposit of whales' bones, and it has been 

 known for sixty years as Suffolk " coprolite," owing to a 

 mistaken notion that it was the petrified dung of extinct 

 animals. It has been dug up by the ton from below 

 the crag all over this part of Suffolk, where it forms, 

 together with bones, teeth, flints, and box-stones, a bed 

 of small nodules, a foot or so thick separating the 

 London clay from the shelly " crag." This bed is called 

 the Suffolk bone-bed or nodule-bed. The phosphorite, 

 or " coprolite," occurs in the form of bits of clay, 

 hardened by phosphate of lime, and of the colour of 

 chocolate, and hundreds of tons of it have been used by 

 manufacturers of the manure known as " superphosphate." 

 Henslow, of Cambridge, Darwin's friend and teacher, was 

 the first to point out its value. Bits of it, as well as 

 box-stones, and fragments of bone, teeth of whales, of 

 sharks, of mastodon, rhinoceros, tapir, and other extinct 

 animals — all fallen from the bone-bed in the cliff — are 

 found mixed with the pebbles of the Suffolk beach by 



