MIDDLE CHAI,K—HAMPSHIRE. 
389 
CHAPTEB XXIX. 
THE MIDDLE CHALK IN HAMPSHIRE. 
General Description. 
The Middle Chalk of Hampshire bridges the broad uplift of the 
Weald, and unites the outcrop which we have traced along the North 
Downs to that which occupies a similar position in the escarpment 
of the South Downs. 
As the mass of the Middle Chalk passes from Surrey into Hants 
the beds lose their northerly dip and receive a gentle tilt or inclina¬ 
tion towards the west, in consequence of which the basset surface 
widens out, so that west of Alton and Selborne it occupies a con¬ 
siderable area of land. Further south it is somewhat narrowed 
but expands again in the valley of West Meon. 
Besides this continuous tract of outcrop there are three other 
areas in the county where Middle Chalk comes to the surface, these 
are—(1) near Winchester (2) the Vale of Ivingsclere, and (3) several 
irregular inliers between the last and the Vale of Pewsey. The 
Winchester inlier is due to a cross roll causing an upward bulge 
or dome on the prolongation of the anticline which runs through 
Pulborough and West Meon. The northern inliers mark out the 
course of the northern branch of the Wealden uplift, and their 
isolation is doubtless due to a series of cross rolls or transverse un¬ 
dulations from north to south, producing troughs or basins in 
which a greater or less thickness of Upper Chalk is brought in. 
If it were not for these local depressions or synclines the outcrops 
of the Upper Greensand and Lower Chalk would have been con 
tinuous from the Vale of Pewsey to the north-western border of 
the Wealden area. 
The Mel bourn Bock occurs throughout the county, and has 
the same characters as in Surrey, so that there is no difficulty m 
following its outcrop. The zones of Rhynchonella Cuvieri and of 
Terebratulina succeed in usual course, but along the eastern 
outcrop great difficulty was experienced in trying to trace the 
zone Qf Holaster planus which does not seem to be represented bv 
anything like the Chalk Bock. 
Near Winchester, however, nodular chalk with Holaster planus 
is fairly well exposed at several points, and was first oberved by 
Professor Barrois. * 
* Recherches sur le terr. Cret. Sup., 1876, p. 41. 
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