470 Notices of Memoirs—Feilsitic Agglomerate. 
along with the sediments entering into the composition of the massif. 
The question then arises whether the accumulation of such quantities 
of radio-active elements may not enter as a factor in the events 
attending mountain-building. It can be shown that an area of sedi- 
mentation whereon has been accumulated some 10,000 metres of 
sediments, having a richness in radium comparable with the Simplon 
rocks, must necessarily become an area of greatly lessened crust- 
rigidity, and would hence become the probable site of crust-flexure 
under tangential compressive stress. 
Further investigation will be required before such views can be 
generalised and the importance of radium as a source of instability of 
the earth’s crust be determined. Apart from any speculations as to 
the influence of radium as the cause of an energetic substratum, the 
shifting of radium and its parent elements by denudation must be 
regarded as a convection of thermal energy, and this convection, if the 
quantities involved are sufficient, must, under the conditions referred 
to above and the unceasing action of denudation, become rhythmic in 
operation, and at the same time must result in shifting the areas of 
high temperature and crust-weakness from age to age as the site of 
sedimentary accumulation changes. 
XII.—Tue Ferstrrc Acctomerate oF THE CHaRNwoop Forest.! By 
F. W. Bennett, M.D., B.Sc. 
fJ\HE rocks lying between the Beacon Series and the Blackbrook 
formation comprise a greater variety than has been hitherto 
recognised. ‘Three main beds can be distinguished, which may be 
called the coarse, white, and pink grits. The pink grit, which is the 
uppermost bed, is the one to which almost exclusively the name of 
‘Felsitic Agglomerate’ has been hitherto given. 
Careful examination of the rocks in the Buck Hills has now con- 
clusively proved that they belong to the Felsitic Series. 
The rocks in the north-west of the Forest have always given rise to 
much difficulty. It is possible to trace the Felsitic Agglomerate as 
a distinct series of rocks in Timberwood Hill. The ground in this 
part of the Forest has been extremely faulted, and a good example of 
this occurs in Collier Hill. 
To the north of the monastery, rocks have now been traced which 
evidently lie on the horizon of the Felsitic Series. They differ in some 
ways from the ordinary agglomerate type, especially as regards their 
texture, which becomes highly crystalline. It is found that these 
Felsitic rocks have been intruded into by igneous flows, both near the 
Cademan area and also in Bardon Hill; and it is probably due to this 
cause that the texture of the rock has been so much altered. 
‘he position of these beds in relation to the Bomb rocks makes 
it probable that they correspond to the Felsitic Series, and this 
correlation is confirmed by comparison of some of the more recently 
discovered types with those of the ordinary Felsitic Agglomerate rocks. 
1 Read before Section C (Geology), British Association, Leicester, 1907. 
