289 
1914-15.] Chalk Boulders from Aberdeen, etc. 
Antrim and Belfast, for specimens of which I am indebted to Mr C. 
Tomlinson and Miss Andrews, the President and Secretary of the Belfast 
Naturalists’ Field Club. The aspect of this rock when viewed as a thin 
section shows that the sediment accumulated under conditions peculiar to 
the locality, and not in complete accordance with the chalk of either English 
or Scottish areas. Mineral grains are here rare; spicules only occur as 
glauconite casts (?) of the axial canals.^ Ehrenberg, however, seems to 
have found Radiolaria in it. 
Whether the boulders have been pushed up by ice from an outcrop 
beneath the waters of the North Sea, or whether they have been derived 
from one occurring on the land to the westward, are questions difficult to 
answer. The general dip of the Mesozoic strata on the east of Sutherland 
is to the east, and if the land was at a higher elevation than it is at present 
it is possible that Cretaceous rocks might be exposed. Now that attention 
has been drawn to the occurrence of chalk boulders at the bottom of the 
neighbouring sea, further investigation may give us information in this 
direction. It is also not improbable that beneath the glacial clays which 
cover so large an area there may remain some fragments of the Cretaceous 
rocks which sooner or later may be brought to the light of day and help us 
to determine the extension of the series to the westward. 
From whatever locality the boulders of Belhelvie were derived, they 
show that the Cretaceous sea must have extended far to the northward 
and that in this northern area the deposit assumed characters which 
distinguish it from the chalk of the south. These characters are 
probably due partly to geographical position and partly to the physical 
conditions affecting the sedimentation. The prevalence of felspars and 
the scarcity of the heavy minerals, as well as the peculiar character of 
some of the finer material, show that the terrigenous material was 
derived from a land differently constituted from that which supplied the 
sand and mud found in the chalk of the south. The absence or com- 
parative scarcity of certain genera of Foraminifera, such as the Bulimines, 
Gaudryinas, Tritaxias, and several species of Textularians common in the 
south, and the incoming of new species not before recorded in the chalk 
indicate that the change in the character of Microzoa, already fore- 
shadowed in the investigation of the chalk north of the Wash is continued 
into this northern area.f 
* W. F. Hume, “The Cretaceous Strata of County Antrim,” Q.J.G.S., vol. liii, 1897, 
p. 584. 
t “The Cretaceous Rocks of Britain,” Memoir of the Geological Survey^ vol. ii, 1903, 
pp. 286, 309. 
VOL. XXXV. 
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