134 Reports & Proceedings—Geologicul Society of London. 
The Chines along the coast of Bournemouth Bay did not originate 
at the cliff-edge and grow inland, as generally stated, but are the 
over-deepened bottoms of older and longer valleys. A similar double 
structure is seen in the Chines of the south-western corner of the 
Isle of Wight, where it is due to the destruction of part of the valley 
of the Yar by the sea since the deposition of the valley gravel; and 
it is suggested that the Bournemouth Chines are due to the breach of 
the Solent River by the sea at the same late period. The 140 ft. 
bluff, running all across Hampshire to the sea-cliff at Goodwood, is 
comparable with the 100 ft. terrace of the Thames, and was probably 
formed in an estuary in pre-Chellean times. 
The rate of recession of the cliffin the western part of Bournemouth 
Bay is estimated at about 1 foot per annum. It may be more in the 
eastern part, but the estimate of 3 yards per annum near Christchurch, 
made in the Natural History of Bournemouth, is probably much too 
high; and the reasons given in that volume for local variations in rate 
cannot be accepted. 
The angle of the cliffs is said to have become steeper of late years ; 
but this is not true of the western part of the bay, and it is desirable 
that the observations on which the belief rests should be published. 
4. February 2, 1916.—Dr. A. Smith Woodward, F.R.S., President, 
in the Chair. 
A lecture was delivered by Richard Dixon Oldham, F.R.S., on the 
Support of the Himalaya. 
He said that it was known that the major prominences of the 
Earth’s surface are in some way compensated by a defect of density 
underlying them, with the result that they do not exert the attractive 
force, either in a vertical or in a horizontal direction, which should 
result from their mass. <A study of the distribution of this com- 
pensation shows that there is a general balance between it and the 
topography, such that the weight of any vertical column through 
the crust of the earth is, on the average, constant, whatever may be 
the elevation of the surface. ‘To this condition the term isostasy has 
been applied, which does not merely denote a static condition, but 
implies a power of adjustment of the compensation to the variation 
in load produced by surface denudation and transport. 
The explanations that have been proposed of the existence of 
compensation fall into two classes. One supposes the relief of the 
surface to be due to an alteration in the volume of the underlying 
rock, and may be regarded as hypotheses of tumefaction. ‘They 
involve no addition of matter to the crust under a mountain range, 
and do not provide, either for any departure from-a balance between 
topography and compensation, or for a restoration of the balance 
when disturbed by denudation. The other group of hypotheses 
attributes the origin of the range to a compression of the crust, the 
injection of molten matter, or the ‘undertow’ of the lower part of 
the crust. To provide for compensation any hypothesis of this class 
will require a downward protuberance of the nether surface of the 
crust, causing a displacement of denser by lighter material, as also an 
