398 
THE CRETACEOUS ROCKS OF BRITAIN. 
in the following section, and others must decide which estimate 
is most correct, but it may be mentioned that the height of the 
cliff at Holywell is given as 249 feet, and as there is Lower Chalk 
at the base the total thickness of the Middle Chalk can hardly be 
270 feet, as Dr. Rowe makes it. 
Places where the lower part of the Melbourn Rock can be ex- 
examined have been mentioned under the head of Lower Chalk 
(see p. 75). The following is a detailed description of the beds 
as measured in and below the Holywell Quarries from the base 
of the chalk with regular layers of flints* : — 
ft. in. 
Zone of 
Ter. 
gracilis. 
White chalk, weathering somewhat rough and 
lumpy, with scattered flints - - about 
Soft creamy white chalk, with occasional thin 
seams of marl ; no flints ----- 
Firm massive chalk in regular courses 
Firm chalk with hard creamy nodules - 
Firm whitish chalk in massive courses 
Layer of yellowish grey marly chalk - 
Creamy white chalk with a few nodules • 
Hard creamy yellow chalk - 
Hard creamy-yellow chalk, courses of smooth 
chalk alternating with beds full of hard nodules 
/Very hard creamy chalk in two massive beds 
Very hard yellowish shelly chalk, with layers 
of hard cream-coloured nodules - 
Course of smoother chalk, separated from the 
adjoining beds by thin seams of marl - 
Two courses of hard nodular whitish chalk, 
( streaked with greenish-grey veins, and 
divided by a seam of marl - 
Course of smooth chalk - 
Two courses of hard nodular whitish chalk 
streaked with greenish grey and divided 
by a seam of marl - - - - 
l Course of hard greyish-white chalk - 
Zone of Act. plenus. — Grey marls (see p. 75). 
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Passing the local anticline south-west of Holywell, where the 
Gault and Greensand rise into the base of the cliff, and rounding 
the point of Beachy Head, we come to where the westerly dip 
finally brings the Middle Chalk down to the beach. (See Fig 27.) 
Here in 1897 the Melbourn Rock was covered by a large 
landslip, but above this there is a complete section up into 
the Upper Chalk. Several layers of yellowish nodules can be seen 
in the zone of Rhynchonella Guvieri, and the shelly chalk of this 
zone appears to pass more gradually into the soft white chalk here 
than at Holywell. The massive beds of the Terehratulina zone 
are generally separated by a thin layer of veiny chalk, which 
sometimes passes into a thin seam of greyish maid, and in the 
upper part there are several layers or bands of marl from 6 to 9 
inches thick. This chalk with marly veins has a thickness of 
95 feet. 
*Mr W. R. Andrews informs us that the chalk with flints seen in 1897 
has since been cut away for the erection of a pumping station in 
connection with the waterworks. 
