470 
THE CRETACEOUS ROCKS OF BRITAIN. 
The Melbourn Rook, 8 or 9 feet thick, with some of the overlying 
chalk, is also exposed in the upper chalk pit on Eoxton Hill, and 
being much weathered its nodular character is very apparent. 
An exposure of the middle part of this zone occurs in a small 
pit by Stanmore Hall, west of Whittlesford, showing 8 or 10 feet 
of weathered rough lumpy chalk containing good typical specimens 
of Rhynchonella Guvieri. 
The Melbourn Rock is seen in the upper level of the large chalk¬ 
pit on Steeple Hill, north of Shelford, and the highest part of the 
zone in the pit below Little Trees Hill, near Vandlebury, the 
section in the latter being : — feet. 
Chalk rubble ----------3 
Hard rocky chalk - ------- 3 
Greyish marl with hard nodules -.4 
Bedded white chalk, with occasional flints and several thin 
jh layers of shaly marl - - - - - - - -18 
Rhynchonella Guvieri occurs in the Maid band. Another pit, 
showing a similar section, occurs on Missleton Hill, north-east of 
Wandlebury, where the bedded white chalk yields more fossils, 
Rhynch. Guvieri, Galerites subrotundus , Inoceramus mytiloides, 
Terebratulina gracilis var. lata, etc. Similar chalk with the same 
fossils was exposed in the railway cutting a mile south-east of Great 
Wilbraham. 
Terebratulina Zone.—The quarries in the lower part of this 
zone near Royston have been mentioned 011 p. 469. East of 
these there are few exposures till the valley of the Cam is reached. 
A pit by the cross roads at Duxford shows 20 feet of thin-bedded, 
platy white chalk, with a very few small flints and a thin seam of 
whitish marl. This is near the base of the zone. Near Ickleton 
there are two pits, one half a mile west and the other three-quarters 
of a mile S.S.W. of the village ; these show thin-bedded white chalk 
with Ventriculites, Inoceramus Guvieri, a species of Micraster and 
of Scaphites . 
Still higher beds are shown in the large quarry at Great Cliester- 
ford, half a mile east of the church ; the section here, as noted by 
Mr. Penning in 1876, was as follows feet. • 
Rather hard splintery chalk - - - - - - - 18 
: Layer of whitish marl - -- -- -- - i 
Bedded white chalk, with a layer of flints about 5 or 6 feet 
i below the marl -.22 
The upper beds contain Terebratulina gracilis var. lata, Gidaris 
spines, and a Pecten. In the lower part fossils are scarce. 
North of Linton there is a quarry in thick-bedded white chalk 
without any flints, but, yielding Micraster Leskei, Holaster 
planus, Spondylus spinosus and Ventriculites. This is in the upper 
beds of the zone. 
Lower beds are seen in a cutting on the abandoned line of rail¬ 
way near Worsted Lodge. These consist of white chalk with many 
flints mostly arranged in bands parallel to the bedding; they 
