Correspondence — Mr. A. O. Cameron. 381 



The brown coal of the neighbourhood, whose natural distillation 

 has most probably yielded the hydrocarbon in the shales, contains : — 



Carbon 49-2 per cent. 



Hydrogen 1*1 ,, 



Water, combined 30 - 2 ,, 



Water, hygroscopic 19 - 5 ,, 



100-00 

 The beds containing these coals have been invaded by eruptive 

 porphyry and trachytic rocks, of which the former contains 75^ and 

 the latter 61 per cent, of silica. 



The clays from which the shales were originally formed contain 

 abundance of marine Diatomaceas and Foraminifera (chiefly Num- 

 mulites), as also species of Ostrea, Cyrena, Cerithium, Voluta, and 

 Nautilus, together with the remains of Placoid and Teleostean fishes. 



COEBBSPOUDBlSrOB. 



WATER-BEARING NODULES IN THE LOWER GREENSANDS. 



Sir, — The brilliant and varied colouring of the Lower Greensands 

 at the Great Northern Railway at Sandy Junction, and at Flitwick 

 Station on the Midland line, must be familar to every one who has 

 travelled those districts. At Sandy, the cutting is a deep one and 

 nearly all in clean sand, varying through shades of green, grey 

 and yellow, the yellow predominating, to almost pure white. At 

 Flitwick, the colouring is still more varied ; beautifully tinted bands 

 of a fleshy pink or salmon tint, merging into violet, appear near 

 the bottom of the pit from which Mr. Franklin, of Bedford, obtains 

 his sand. The parti-coloured bands are more numerous at this place 

 than I recollect seeing elsewhere in Bedfordshire, although the white 

 and yellow sand at Heath and Beach, makes very picturesque open- 

 ings amongst the woods and ferns. The sands at Flitwick remind 

 one of the assemblage of colours met with in the sands, 1 from which 

 the well-known sand pictures are made in the Isle of Wight. 



But besides the varied colouring, ironstone nodules, associated 

 with hard lumps of ferruginous rock, like the carstone quarried at 

 Snettisham in Norfolk, are very general in the Greensand. Being 

 of all shapes and sizes and in every stage of growth, they are 

 curious to look upon, and still more interesting to crack for the 

 fossils and sparry crystals that are sometimes found inside them. 

 An abundance of these concretions occurs both at Sandy and Flitwick, 

 some spherical, others tabular, and many other forms. 



With Rhodes, the fossil collector, I have lately obtained a number 

 of these nodules from Flitwick, 2 some of which, for description sake, 

 and from the fact of their having water in them, I have designated 

 water-bearing nodules. These are readily distinguished from others 

 inclosing phosphatized fossils (principally the internal casts of some 



1 Bagsbot Sands. 



2 From the peat at Flitwick I picked out, last year, a small flint implement. 



