1850.] PRESTWICH ON THE LOWER TERTIARY STRATA. 2/3 



Organic remains of stratum *'e," at Kyson^. 



Macacus eocsenus, Owen. Cheiroptera. 



Didelphys ? Colchesteri, Charlesworth, Teeth of Lamnae. 

 Hyracotherium cuniculus, Owen. 



I have found slight traces of fossils in the clay bed " 5," but they 

 were too imperfect for determination. 



A larger section of the London clay is worked near Melton Street, 

 two miles north-east of Woodbridge. 



Beyond Woodbridge to the coast the Eocene strata are continuously 

 overlaid by the Crag, and sections of them become still less frequent. 

 On the coast the cliffs at Bawdsley show a section of red crag reposing 

 on the London clay, but these clifFs are not continued to that point 

 (probably not far northward) where the beds below the London clay 

 would crop out. 



"We have now traced this basement bed of the London clay at in- 

 tervals in a belt wrapping round the tertiary series for the length of 

 250 miles. 



In the central portions of the tertiary district, the base of the 

 London clay, although not exposed, is reached in many well-sections. 

 Everywhere the same leading features as we have shown to exist at 

 the outcrop, present themselves at greater depths. 



The organic remains found in this stratum, unlike those of the 

 London clay, which so generally exhibit internally some form of 

 pyritical or calcareous infiltration giving the fossil a solid form, are 

 usually extremely friable, and have rarely undergone any mineral 

 substitution. The ordinary material of the rock passes into the 

 interior of the shell. The shell itself is almost always preserved, 

 although in a very earthy and friable condition. Still, where care is 

 taken, or when they are imbedded in calcareous masses, they can be 

 obtained in a very perfect state. 



Owing to the persistent range of this bed and its distinctive cha- 

 racter, I have, to give it a definite designation for the convenience of 

 reference, termed it " the basement bed of the London clay," although 

 viewing it always merely as a subordinate member of the London 

 clay. 



Conclusion. 



The preceding descriptions I believe embrace, with two or three 

 exceptions, all the principal sections exhibiting the superposition of 

 the basement bed of the London clay. Although, considering the 

 extent of the line of outcrop, they are not very numerous, the intervals 

 between them are sufficiently short to trace this deposit from place 

 to place with considerable certainty. The details of each may vary 



* These fossils are as rare as they are curious. They have been found chiefly 

 by the careful and minute search instituted by Mr. Colchester, who, I believe, had 

 the sands and pebbles (" c ") frequently sifted and examined on purpose. A like 

 close examination might possibly bring to light similar fossils at other localities, 

 especially at those where the structure so nearly resembles that at Kyson (as in 

 figs. 17, 18, & 19). So scarce are these fossils, that in the short visits I have 

 paid to all these pits (Kyson included), 1 have never found anything but the 

 teeth of the Lamna. 



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