UPPER, OR FLINTY CHALK. 153 



had been squeezed out of the beds, and had run into the fissures as soft 

 pitch would do : I do not mean that this was the case, but merely to de- 

 scribe the appearance *." 



Steyning chalk-pits. These produce belemnites, plagiostomae, dian- 

 choree, teeth, palates, &c. The sulphuret of iron found in these 

 quarries is of a very singular form, being cylindrical, with a small projec- 

 tion at both extremities ; a specimen is represented in tab. xvi. fig. 16. 



MINERALS. 



The minerals of the upper chalk are but few in number, and like the 

 lower chalk, it contains but one metaUiferous ore. 



1. Crystallized quartz : this is of frequent occurrence in the cavities of 

 siUceous nodules, shells, &c. The form of the crystals is that of a six- 

 sided pyramid, their colours varying from a reddish brown to a light blue, 

 amber, grey, and white. 



2. Chalcedony, is often found occupying the hollows of flints, and is 

 either mammillated, botryoidal, or stalactitical. It sometimes forms the 

 constituent substance of corallines, alcyonites, and other zoophytes, dis- 

 playing in the most delicate manner the complicated structure of the 

 originals. Its colour is of various shades of grey, azure, and pearl white, 

 and in many examples it is beautifully translucent : specimens are not un- 

 common, in which the surface of the mammillated chalcedony has received 

 an investment of crystallized quartz. 



The stalactitical and botryoidal varieties, are confined to those nodules 

 which retain a part of the original zoophyte. In some instances the flint 

 passes insensibly into chalcedony; in others the line of separation is most 

 distinctly marked; but in all, there is suflicient evidence that the chalce- 

 dony and quartz were deposited by infiltration, and must have passed 

 through the substance of the flint. 



* Linnean Transactions, Vol. vi. page 108. 



