1886-87.] Fossils of Red Crag and Chalk Pits, Suffolk. 53 



The well -known red crag phosphates of Suffolk are scarcely less 

 interesting to geologists than those of the south of France. They occur 

 as nodules, often enclosing fossils ; but, singularly enough, these fossils are 

 never those of the red crag itself, but always those of the much older 

 " London clay " formation. These crag phosphatic nodules still go by 

 the name of "coprolites," from an antiquated but erroneous opinion that 

 they are the fossil excrement of animals. Instead of this being their 

 origin, however, we know that they represent that portion of phosphorus 

 which has entered into the structures of the soft bodies of those very 

 animals whose hard parts, as bones, shells, &c., also occur in the fossil 

 state ; in fact, they are phosphuretted hydrogen set free from the decom- 

 posing bodies of the animals which died in the sea along whose floor the 

 "London clay" was deposited. Phosphoric acid, so forming, combined 

 with lime, and in this manner the nodules of phosphate of lime were 

 formed by segregation. 



Here is another short extract bearing on the same topic, from 

 Dr Taylor's ' Geology of Ipswich ' : — 



There is every reason to believe that the so-called coprolites or phos- 

 phatic nodules were in reality accumulated on an old exposed land-suTface 

 of the " London clay," before the area was submerged to form the bed of 

 the red crag sea. Teeth of " mastodon," rhinoceros, and deer are not un- 

 frequently met with, associated with bones of older date. 



Fossil wood, as well as bones, teeth, &c., of animals, chiefly 

 cetaceans, are met with in the " crag," these having been re- 

 deposited in the crag beds after having been washed out of the 

 London clay in which they were originally embedded. I am 

 indebted to Dr J. E, Taylor for several specimens of Otoclus 

 ohliquus (shark's teeth) which are shown to-night, as well as 

 for the beautiful " box-stone " containing Pectunculus glyci- 

 meris. The nature of these box-stones will be best described 

 in Dr Taylor's own words : — 



Very singular are the roundish masses of coarse sandstone which are 

 met with at the Foxhall Crag Pit. From Foxhall, the bed containing 

 them, which usually lies directly on the " London clay," extends to 

 Felixstowe, and heaps of them may be seen by the roadside, waiting to be 

 broken up for road-mending. They are very curious as representing a 

 lost formation, older than the "coralline crag," for they are also found 

 under it, which is probably of late Miocene age. It is the quarrymen 

 who have termed them "box-stones." You strike them with a sharp 

 blow of the hammer, and about one in every ten will break in halves, 

 revealing the cast of a fossil shell within. These " box-stones " are the 

 broken-np and rolled remains of a bed of sandstone which once covered 

 this part of Suffolk, and which still underlies Antwerp, Brussels, and other 

 places in Belgium. 



