SECTIONAL TRANSACTIONS.—C. 309 
SECTION C.—GEOLOGY. 
(For references to the publication elsewhere of communications entered in the 
following list of transactions, see page 389.) 
Thursday, August 27. 
Morninc. 
1. Presidential Address by Prof.W. A. Parks on The Cultural Aspects 
of Geology. (See page 55.) 
2. Dr. W. Rak Suerrirrs.—Geology of the District round Southampton. 
3. Mr. Henry Bury.—The Rivers of the Hampshire Basin. 
The synclinal fold which has helped to preserve the Eocene Beds of the Hampshire 
Basin has also determined its main river system. The former longitudinal-consequent 
river (Frome-Solent) has been largely obliterated by the sea, but many of the tribu- 
taries, which ran down the slopes on either side, still remain, especially on the northern 
(mainland) side. These, owing to the asymmetry of the main syncline, are longer and 
more important than those on the south. As a rule such mainland rivers cut right 
across the minor folds which flank the central valley, but in the more northern (chalk) 
areas several small synclinal rivers occur, which Mr. Osborne White regards as 
remnants of an earlier longitudinal drainage, but which may be only subsequent 
streams, arising after the former Eocene covering had been denuded off the anticlines. 
But although the main transverse rivers have all the appearance of © consequents,’ 
the late Mr. Clement Reid* regarded the Avon as having arisen in two parts—the 
Upper Avon having reached Southampton Water (‘Southampton River’) by way of 
the Blackwater, until it was captured by the Lower Avon. None of the usual signs 
of capture are present, but Clement Reid relied on (1) an alleged alignment of 
the ‘Salisbury Rivers’ with Southampton Water; and (2) the ‘extremely rapid 
lowering ’ which ‘ must’ have occurred in the Lower Avon valley, when the Solent 
River was breached by the sea. As regards (1), only the Wylye and a small portion 
of the Nadder follow this line, and the alignment of the Upper with the Lower Avon 
is at least as good ; while as to (2), no appreciable lowering would follow if the breach 
was made when the Solent valley was an estuary, and its tributaries more or less 
“drowned ’ by the sea (compare the present condition of the East and West Yar, 
in the Isle of Wight). The ridge of plateau gravel between Woodfalls (near Downtown) 
and Picket Corner, which Clement Reid regarded as marking the course of the old 
river, runs wphill, and is moreover continuous with gravel attributed, by that author 
himself, to the Avon in its present single form. 
The hypothesis of a double origin for the Avon has therefore nothing whatever 
to support it. On the other hand, we see in the striking escarpment of Bramshaw 
evidence of recent activity in the Blackwater, due no doubt to the shortening of its 
course to the sea when the latter invaded Southampton Water ; and it is by no means 
inconceivable that this may in time lead to the capture of the Upper Avon by the 
Blackwater—a complete reversal of the process imagined by Clement Reid. 
The exact stage at which the Solent River was breached by the sea cannot be 
determined ; but the evidence points to a fairly recent date. It is certain, however, 
that before that time the sea had more than once invaded the valley past Spithead, 
and it is very desirable that the details of those advances should, if possible, be worked 
out, as otherwise we cannot determine the relative altitudes of the gravel terraces in 
different parts of the river system. 
4, Mr. E. H. Davison.—The History of Cornish Mining in relation to 
the Geology of Cornwall. 
The history of Cornish mining is a record of progress in mechanical invention 
making it possible to work new types of ore deposit ; it is also intimately related to 
the geological structure of the district. 
* <The Geology of the Country round Ringwood.’ Mem. Geol. Surv. (Sheet 314). 
By Clement Reid. 1902, pp. 29-32. 
