380 Sir H. Bunbury, Bart.^ on the Strata at Mildenhall. 



The chalk lies very near the surface on the spot where the trial was made, 

 being- covered by a rich sandy loam, to the depth of from twelve to eighteen 

 inches only. The workmen bored through the common white chalk to the 

 depth of thirty-five feet ; and then through a layer having a yellow tinge 

 and gritty to the touch, five feet in thickness. Below these lay the gray chalk, 

 harder than the foregoing, and 136 feet thick. Next came blue clay, fifty-four 

 feet thick, and then a layer of darker and heavier clay about ten feet thick, 

 which approached in hardness to stone. This changed gradually into a stony 

 mixture of blue clay with greenish quartzose sand, which was nearly of the 

 same depth. Beneath lay ten or eleven feet of green sand, containing frag- 

 ments of various fossils, and particularly of belemnites and pentacrinites. 

 On descending, the blue clay re-appeared ; but this lower bed abounded in 

 fragments of large shells, having a high polish. The workmen had pierced 

 through nine or ten feet of this clay, when the water of which they were in 

 search rushed in, and the labour was discontinued. The water however, 

 though it has risen in the shaft very nearly to the surface, has not overflowed ; 

 so that the experiment has failed of the intended purpose. 



The action of the boring machine, and the small diameter of the perfora- 

 tion have been unfavourable to the ascertaining of the fossils of the several 

 strata. Fragments of the stalk of the pentacrinite were the most perfect of 

 the specimens. Among the broken fossils in the green sand, some were 

 pyritical. 



Recapitulation of the Strata. 



Feet. 



1. Sandy loam .... 1 



2. Common white chalk, without flints 35 



3. Yellowish, gritty chalk . 5 



4. Gray, hard chalk . . .136 



5. Blue clay .... 54 



6. Darker and harder ditto 10 



7. Blue clay mixed with green sand 10 



8. Green sand with many fossils . 1 1 



9. Blue clay with fossil shells . 9 



271 

 Believe me. 



My dear Sir, 



Very faithfully yours, 



Henry Bunbury. 



