SECTIONAL TRANSACTIONS.—C. 377 
variation in thickness, represent a self-registration of years and of the annual 
radiation from the sun. This registration is specially discernible where 
marked seasonal variations during the final stage of the Ice Age every 
summer gave rise to an accentuated flood of melt-water, depositing an 
annual varve of clay. Such varves are now found on the bottom of late 
Quaternary inland seas or ice-dammed lakes with brackish or fresh water. 
Here, the more heavy, cold and muddy melt-water currents follow the 
bottom, registering every seasonal variation in the transporting power of 
the water by a cyclic lamination. At open coasts with more heavy salt 
water the clay was carried out along the surface, and no varve cycles were 
formed. 
By means of mapping, measurements, photos and lantern slides it is 
possible to illustrate this process of sedimentation. By comparing long 
series of annual varves a definite connection has been found, and this was 
so reliable that certain overlooked varves could be noted, and afterwards 
found to exist in their right place and number. As such correspondence 
was observed between the northern and southern hemispheres as well as 
under the equator, this proved that all the Quaternary glaciations were 
synchronous and not alternate, as supposed on several astronomic assump- 
tions. The widespread and rapid annual variations exhibited by the clay 
varves indicate, as a cause, the annually varying amount of heat from the 
sun. The normal variations may depend on a varying amount of meteoric 
matter in space, more or less obscuring the radiation from the sun. Biennial 
variations conclusively established, but independent of each other, may 
indicate some biennial arrangement of the obscuring dust, as in the case of 
the cometoids. 
Varve connections have been published for all the Fenno-Scandinavian 
countries, Scotland, Iceland, United States, Canada, the Alps and the 
Himalayas, British East Africa near the Equator, and, in the southern 
hemisphere, Patagonia. 'Teleconnections have been determined, but not 
yet published, in the southern hemisphere (New Zealand) and in the 
northern hemisphere (Newfoundland and some parts of Russia and Siberia). 
Dr. W. J. ARKELL.—A reinterpretation of the Purbeck and Ridgeway 
faults in Dorset (10.30). 
The interpretation of the Purbeck and Ridgeway Faults as thrust faults 
from north to south, accepted for the last 40 years, is untenable. The 
only thrusting has been on a trivial scale from south to north, as shown at 
Durdle Cove and Swyre Head. The Purbeck Fault at Ballard Point can 
be best explained as a normal fault downthrowing north. It does not 
_ teach the sea between White Nothe and Bat’s Head, near Lulworth, as 
marked on the Survey map, where only a synclinal bend in the chalk can 
_ be found, accompanied by crushing in the axial plane. 
The Ridgeway Fault is accompanied by a belt of shattering and upward 
drag in the chalk to the north of it, and downward drag and contortions 
with small reversed faults are shown to exist in the Purbeck Beds adjoining 
iton the south. Hence it is inferred that the Ridgeway Fault is a reversed 
fault upthrown on the south side. At its western extremity it almost 
coincides with the Abbotsbury Fault, a normal fault of intra-Cretaceous 
age downthrowing south about 700 ft. The two faults are believed to 
tun approximately parallel for five miles and to scissor across east of Upwey. 
The inliers of Oxford Clay and Lower Oolites at Ridgeway and Bincombe 
are explained as a wedge of rock that has remained on the upthrow side of 
both faults and been bared locally by erosion. The famous ‘ dyke’ of 
