TRANSACTIONS OP SECTION C. 1S7 



the presence of basic igneous rocks,-* but there seems to be considerable room 

 for research as to the rehition between these phenomena and the form and com- 

 position of an igneous intrusion. 



In this review of some of the possibilities of geological research I cannot 

 claim to have done more than touch the fringe of the subject. In every 

 direction there is room for the development of fresh lines of investigation, 

 as well as for renewed activity along paths already trodden. Whether my 

 particular suggestions pi'ove fruitful or not, they will have served their purpose 

 if they have stimulated anyone to look for new fields of work. 



Postcnpt. — Since this Address was written, I have learned that Professor 

 K«ndall has from time to time made valuable suggestions with regard to the 

 association of the Survey with local workers, more especially the geological staff 

 and students of our colleges. 



The following Papers were then read : — 



2. The Tertiary Beds of Bourriemouth and the Hampshire Basin. 

 By Dr. William T. Ord, F.G.S. 



The physical history of these Eocene beds is briefly as follows : — The gradual 

 uprising of the bed of the Cretaceous sea was in this district accompanied by 

 a planing off of the highest zones to some distance down the Belemnitella zone. 

 This left an eroded surface on which the earliest Tertiary beds (Woolwich and 

 Reading) were deposited. Flint pebbles, once rolled in chalk-enclosed coves, 

 form a basement bed. As the new chalk land-surface developed, a west-to-east 

 drainage system rapidly formed, which during the next period — London Clay — 

 took the form of a vast river, rivalling the Ganges or Amazon. It entered the 

 sea near Sheppey, in Thanet, where tropical vegetable flora and estuarine fauna 

 have left abundant remains. Here the fluviatile beds — of sand and clay, with a 

 few pebble bands — are almost unfossiliferous. This is true locally for each 

 division of the Tertiaries, following the usual rule of fluviatile deposits, the nearer 

 the mouth the more organic remains, the nearer the source the fewer. Since 

 Bournemouth occupies a place far from Sheppey, fossils are few or wanting. 

 The exception are leaves and fruits which have been deposited in clay bottoms 

 of backwaters and lagoons, and hence occur in lenticular patches in the cliff 

 face. 



In the succeeding beds — the Bagshots — abundant vegetable remains occur. 

 During this period the sea continually encroached from the east, rmtil at the close 

 of the Bagshot period it is believed to have reached a point near the East-cliff 

 Lift. The shingle-beds of the Bracklesham (Boscombe Sands) covering the 

 Bagshots were a beach deposit. The succeeding Bracklesham deposits, locally 

 known as Hengistbury Head beds, are followed by the Barton sands and clays: 

 these are increasingly marine, and their organic remains show a marked fall of 

 temperature from the sub-tropical climate of Bagshot ase. The succeeding 

 strata. Headon beds and 01ia;ocene, concluded by the Bembridge Limestone, occur 

 in the Isle of Wight and the Headons, also in the opposite coast. These were 

 denuded off the Bournemouth area in Miocene times, except for an important 

 outlier in Purbeck known as Creech Barrow. All these Eocene strata were 

 deposited over a far greater area than they now occupy, and their remains have 

 been preserved in the Thames Valley and Hampshire Basin throush the pro- 

 tection afforded bv the results of the preat earth movements of Miocene and 

 Pliocene times. The Chiltern Hills and North Downs protected the Tertiaries of 

 the Thames Valley, and the South Downs and the Brixton anticline of the 



-" A. Hubert Cox : Abstracts of the Proceedings of the. Geological Society of 

 Lour/ on, 1918, pp. 71-74. 



