Revieius — Geology of Fareham and Havant. 279 



The western end of the South Downs runs through the northern 

 purt of the district. To the north of this ridge the Gault and Lower 

 Greensand come on in the Wealden area near Petersfiehl. To the 

 south the ground slopes gently to the wooded track of the Forest of 

 Bere on Eocene strata. Southward again from this tract conies the 

 Chalk ridge of Portsdowu, which declines eastward and westward 

 from a point above 400 feet near Southwick. 



The lowest strata exposed in the district are the Sandgate Beds, 

 which occur near the north-eastern corner and are believed to be 

 about 70 feet thick. The succeeding Folkestone Beds here consist of 

 yellow and white sands, with seams of carstone near the middle ; they 

 are not known to be fossiliferous, their thickness is locally about 

 150 feet. The Selbornian, comprising the Gault and Upper Green- 

 sand, is grouped under zonal headings, and most of the local Gault 

 clays are considered to belong to the zone of Eoplites inferruptus. 

 The Greensand immediately below the Chalk is not well exposed ; it 

 was not seen eastward of Barrow Hill within the present district, but 

 it may be continuous with the similar deposit observed south of 

 Petworth. 



Four chapters are devoted to a consideration of the Chalk. This 

 formation occupies rather more than half the country, and probably 

 attains a thickness of 1,200 feet in the southern part of the district, 

 where it is most fully developed. The junction of the Upper and 

 Middle Chalk is somewhat difficult to trace in the field, as there is 

 no hard band of Chalk llock at this horizon as in other districts. 

 The line on the map has been drawn at the base of the markedly 

 flint-bearing beds or rather below the actual top of the Middle 

 Chalk. The generally accepted zones of the English Chalk have 

 been recognized, and due note is taken of the recent work of 

 Messrs. Griffith and Brydone. 



With regard to the Lower Chalk, this is confined to the northern 

 part of the area. Its lowest member, the so-called Chloritic Marl, is 

 about 3 feet thick ; this is followed by bluish marls belonging to the 

 zone of Schloenbachia varians; the succeeding zone of Holaster sub- 

 giohosus is composed of yellowish-white chalk. The top of the Lower 

 Chalk is plainly marked by the Actinocamax plenus Marls. The 

 thickness of the Lower Chalk is estimated at 220 feet. 



In the Middle Clialk the Melbourn Rock appears to be represented 

 by a bed of firm sub-nodular wliite chalk, 2 to 4 feet thick at the 

 base of the Ctivieri zone, which here consists of alternations of lumpy 

 white chalk and of thinner roughly laminated marly chalk. The zone 

 is about 70 feet thick. The Terehratulina lata zone consists mainly of 

 white chalk with some thin seams of grey marl, and contains a good 

 number of small flints. It is about 120 to 130 feet thick. The total 

 thickness of Middle Chalk is about 200 feet. 



The Upper Chalk in the southern part of the district is probably 

 about 750 feet thick. It here comprises six zones, from Holader 

 planus to Beleinnitella mucronata inclusive. The greater ])art of the 

 last-named zone is, however, missing, owing to erosion in early Eocene 

 times. The zone of Holaster planus is composed of distinctly nodular 

 chalk ; flints are common, small, and with thick rinds. The sub-zone 



