— 
1870. ] SHARP—NORTHAMPTONSHIRE OOLITES. 363 
ft. in. 
-3. A bed of a peculiar character, consisting of alternate layers of calca- 
reous and arenaceous material, each about half an inch in thick- 
ness, the former standing out in ridges when weathered. 
These layers are sometimes horizonal, and sometimes much and 
variously inclined from false bedding ..................csceeceseeeeees 3 0 
4, Hard, irregular, finely laminated, shelly zone, with much carbonate 
of lime—contains Acrosalenia Lycettté and many oysters and other 
shells. This zone is not constant .......0......:.sseecereeeceeesceeeees 0 9 
5. Thinly laminated bed of alternate layers (as bed 3), but the false- 
bedding much more marked, sometimes inclined from right to 
left, and sometimes from left to right, in alternate zones......... 2 0 
6. Similar bed, not so finely laminated, and with false-bedding, uni- 
form in direction and less marked. Some fossils ................+ 3 0 
7. Hard arenaceous limestone, in two beds, false-bedded, and 
becoming slaty towards the bottom ................esesnee 5ft.to 6 O 
One noticeable peculiarity in this section is the prevalence of 
false-bedding, inclining frequently in opposite directions in alternate 
bands, indicative of strong and diverse aqueous currents during the 
process of deposition. Another is the perfect manner in which the 
tests of shells have been preserved in the sandy zones. This I have 
found to be the case elsewhere, and indeed generally, in such 
zones. 
Prominently noticeable also is the presence of several vertical 
pipes, of from a few inches to nearly 3 feet in diameter, which have 
penetrated through the whole of the calcareous beds—doubtless the 
effect of the dissolving action of water charged with carbonic acid. 
These are to be seen in section on the face of the pit: they have 
been filled, partly with the arenaceous residuum of the rock, partly 
with the sand of bed no. 2, and partly with material brought down 
by percolation from above. 
It is curious that in every case these pipes are bridged over by 
the layers of the ferruginous bed at the top of the section ; upon 
the non-calcareous material of which, in its passage through it, 
the water charged with carbonic acid has had no solvent effect. 
Another section of this division of the Northampton Sand is 
exposed in a pit near Boughton (marked h), at a distance of a mile 
and a half N.N.E. from this Nursery pit, and on the other side of 
the high ground in which are the pits first described. Here the 
section, about 20 feet in thickness, consists wholly of calcareous 
rock, divided into some half-dozen beds, containing few fossils, but 
showing false-bedding near the bottom. 
The calcareous condition of these beds is persistent over a con- 
siderable area lying in this direction; and they are largely quarried 
for building-stone, which is very durable and of a good colour. 
A few hundred yards south-west of the Nursery pit, is the Kings- 
thorpe brick-pit (7). Here is seen the base of the Northampton 
Sand immediately overlying the Upper Lias Clay. It presents a 
section of from 6 to 8 feet of the Northampton Sand, and supplies a 
continuation downwards of the section of the Nursery pit. 
Under a bed of about two feet of weathered rubbly brown 
sandstone is a soft arenaceous bed (also about 2 feet thick) contain- 
22 
