1868.] BAUERMAN AND FOSTER CELESTINE. 41 



The brown beds at the top of the escarpment are so irregular in 

 their appearance that it is difficult to continue the section ; probably 

 there are from 20 to 30 feet more of similar beds at the top of the pla- 

 teau. The lowest bed (No. 1) appears to be that regarded as forming 

 the top of the chalk by Dr. Figari Bey. 



One of the most marked horizons in the whole section is what may 

 be called the big-Nummulite bed, which contains the large species of 

 Nummulites, examples of which may be found up to 2| inches in 

 diameter. It lies about 80 feet below the junction of the white and 

 brown beds, a position corresponding to the lower part of bed No. 4 

 in the above section. 



Along the lateral valleys the gypsum-marls (No. 9) have been 

 subjected to considerable atmospheric degradation, and large pieces of 

 celestine are common in the talus formed by the waste of the hill. 

 They are partially rolled, of a dull bluish-grey colour, and compact, 



forming either long prismatic forms, from the combination OP . oo Poo , 

 or similar combinations tapering to one end, having formed part of a 

 spheroidal aggregate of crystals, terminating externally by the planes 

 of the diagonal prism oo P. On examining the cliff-section these 

 spheroids or nodules are found in place in the sandy limestones and 

 marls, together with fibrous gypsum. They show a roughly stellar 

 aggregate of crystals, with a dull earthy centre, the largest examples 

 being about 4 inches in diameter. 



The following (p. 42) is a measured section of the principal celes- 

 tine-bearing beds where they are well-developed ; it is taken in a 

 gulley behind the main escarpment. In addition to these there is 

 another bed with nodules of celestine, a few feet below bed No. 10. 



About 30 feet below the junction of the white and brown Nummu- 

 litic beds there is a very singular development of celestine crystals 

 in the hollows of a white fossiliferous limestone. They are mostly 



long prisms of the open form OP . Pgo , often of considerable size (up 

 to 4 or 5 inches in length), and almost always very rough and decom- 

 posed about the ends in the plane of the prismatic faces go P. Besides 

 the simple crystals, macled groups of two, arranged similarly to the 

 diagonal cuneiform twins of Staurolite, and similar combinations of 

 three or more crystals of greater complexity are found, although not 

 quite so abundantly as the former. In either case, however, the 

 surfaces of the crystals generally seem to be incrusted with fragments 

 of shells, Bryozoa, and small Nummulites, as though they had formed 

 points of adhesion for these organisms. But that this is not the 

 case, is proved on closer inspection, as the shells often pass right 

 through the crystal; and on subjecting some of the more perfect speci- 

 mens to cleavage, transparent plates were obtained with Nummulites 

 enclosed. It is evident, therefore, that the fossils must have been 

 entangled in the crystals at the time of their formation, and that their 

 subsequent exposure is due to the action of solvents, which have 

 removed the sulphate of strontia, leaving the carbonate of lime, 

 forming the shells and Nummulites, untouched. The hollows in which 

 the crystals are found are generally empty, owing to the original 

 contents having been partly removed by the action of the atmosphere ; 



