LOWER CHALK —CAMBRIDGE AND SUFFOLK. 
199 
Tlie Totternlioe Stone is also quarried at Isleliam, 6 miles north¬ 
east of Bur well, the upper beds being seen in the quarry south of 
the church ; here the massive blocky stone is overlain by 2 or 3 feet 
of hard rough grey chalk, in several irregular beds, the material 
being a mottled mixture of dark and lighter grey chalk. Above is 
firm greyish-white chalk, and there is nothing like the “ bond ” 
course of Burwell. 
Chalk above the Totternhoe Stone. 
As the Belemnite marls are frequently exposed in pits which 
also show more or less of the underlying chalk, it will be convenient 
to take them together, instead of separately. The first good section 
in Cambridgeshire is in a quarry about half a mile south of Litling- 
ton, and the chalk is so worked that the two faces of the pit form 
two sides of a triangle, the apex of which points N. : 3ST.E. 
On the easterly side the section is : — 
ft. 
Melbourn Rock - - - 10* 
{ Grey marly chalk, passing down into laminated marl 2 
Hard grey and white “marbled rock,” containing 
Actinocamax plenus and other fossils 1 
Greyish marly chalk, passing into that below 2 
Rather hard white chalk (see p. 190) - 6 
Gritty chalk with green-coated nodules - 1 
Whitish chalk below. 
The “ marbled rock ” or chalk conglomerate thins out toward 
the apex of the triangle, and the upper marl thickens somewhat, 
so that along the northern face the zone consists entirely of grey 
marly chalk and shaly marl, and is nearly 5 feet thick. 
Another good exposure is in a quarry south of Melbourn, where 
the dip is 5° to the south-by-east, and the beds seen are 
ft. 
Belem¬ 
nite 
Beds. 
Melbourn Rock and chalk above- - 
Buff laminated marl. 
Grey marly chalk ------ 
)Hard compact white chalk ----- 
[Grey marly chalk ------- 
White chalk, rising to the north-west, and seen for about 
17 * 
1 
2 
2 
1 * 
26 
50 
The Belemnite Beds are here unusually thick (6* feet), and 
at the northern end of the pit the compact white chalk passes 
into the brecciated nodular condition above described. In another 
pit only a quarter of a mile from the above this band has its normal 
thickness (little more than 3 feet) and its usual composition. 
These beds are seen again in a pit on Maggots Mount, near 
Harston, where they have a thickness of 5 feet or more. 
A quarry on Steeple Hill, north-east of Shelf or d, gives a good 
section of the upper part of the Lower Chalk. The beds seen in 
the upper level are : — 
