166 Mr Rastall, The Minerals of some Sands ] 
i 
very similar to that from Newmarket station, and unlike the 
sands near Cambridge. The chief minerals identified are zircon, — 
rutile, garnet, hornblende, augite, epidote and staurolite. Tour- 
maline is notably scarce and kyanite was not found. | 
The grains of garnet, though larger than most of the other — 
minerals, are still small and generally a good deal rounded, while 
the crystals of epidote, of a bright yellowish green, are conspicu- | 
ously round. The hornblende includes not only the common 
green variety, but also a blue form, referable to arfvedsonite. 
The most notable feature of the specimen is certainly the extra- 
ordinary abundance of zircon and the extreme rounding of many 
of the crystals of this very hard and resistant mineral, indicating — 
prolonged rolling, or derivation in a rolled condition from some | 
older rock. The entire absence of kyanite and rarity of tourmaline — 
are also notable and difficult to explain, since both these minerals — 
are so abundant in the sands of the same general age near — 
Cambridge and both occur with fair frequency in the sample of — 
sand taken from another part of the same pit. This fact goes to — 
confirm the idea that sands of two different origins and ages are — 
exposed in this pit. 
(4) Pit near Eaning Village. 
This pit is situated a short distance from the village of 
Exning, on the road to Snailwell, and lies on fairly high ground. 
It shows a good exposure of material of peculiar character, which 
is best described as brown and grey loam or marl, or the somewhat ~ 
vague designation of brick-earth might well be applied to it. 
Although the material is of very fine texture it contains a few | 
large flints, those of an elongated form often lying with their long 
axes vertical. There are also well rounded boulders of sand up to- 
a foot in diameter embedded in the marl. The occurrence of the 
vertical flints and of the boulders of sand suggest deposition from 
floating ice in comparatively still water. It is difficult to account 
for the sand boulders unless they were frozen when deposited in 
their present position, as they are well rounded and with sharp 
outlines clearly demarcated from the fine marl. 
Two large samples were taken from this pit, one of a brown — 
loamy material and the other of a fine greyish-yellow sandy marl, — 
The treatment of these samples presented considerable difficulties, — 
owing to the large amount of fine mud. However by long- © 
continued washing in a large porcelain dish the mud was eventu- 
ally got rid of, and the sandy residue could be treated in the usual 
way. Naturally this residue was of unusually fine grain, and did — 
not submit to the operation of panning so readily as the coarser 
sands. In the case of the fine marl in particular the amount of — 
heavy minerals ultimately obtained was very small. 
