J. H. A. Whealler—Boulders of Cambridge Gravels. 203 
It is of interest to note that a boulder collected some time ago 
at Whitby by Dr. Rastall bears a marked resemblance to the 
Bredvad (Dala) porphyry, described by Milthers. 
Turning now to the Scottish types many interesting specimens 
have been collected. 
Firstly, we have the quartz-porphyry from Buchan Ness. This 
rock has fine phenocrysts of orthoclase, and plentiful quartz grains 
embedded in a dark, fine-textured groundmass. It is recorded 
by Rastall and Romanes as being found at Barrington, an exposure 
now unfortunately largely overgrown. The Barrington specimen 
was identified as the Buchan Ness rock by Dr. Bonney and Dr. R. 
Campbell. This year three specimens have been recorded from the 
Travellers’ Rest Pit, but I am not aware of any having been found 
here previously. Two of the specimens were moderately large and in 
good preservation. 
The next rock of interest is a beautiful alkali-granite with fine 
crystals of pink felspar and occasional patches of dark ferro- 
magnesian mineral. I submitted this specimen to Dr. Bonney, who 
remarked on its strong affinities to both the Ross of Mull and Peter- 
_ head granites, the resemblance to the latter being more pronounced ; 
the possibility of its being a specimen of the former being out of 
the question, and the finding of thé Buchan Ness rock just referred 
to, seem to indicate its being of Peterhead origin. One specimen 
only has been recorded. 
The finding of the Buchan Ness and Peterhead rocks here gives 
excellent proof of the presence of North Aberdeenshire erratics 
in the Cambridge drift, and touching on the interesting question as 
to how they reached this district, new facts have lately come to 
light. On the map on p. 49 of Mr. W. B. Wright’s Quaternary 
Ice Age, the ice flow on the North Aberdeenshire coast is shown as 
roughly northerly. From this the inference might be that these 
types were transported indirectly, had it not been for a recent 
important discovery. In the report of a recent meeting of the 
Edinburgh Geological Society + there is an account by Dr. Bremner 
of the finding of a boulder of rhomb-porphyry at the Bay of Nigg, 
just south of the town of Aberdeen, and about 30 miles south of 
Buchan Ness. This discovery is of the utmost importance, showing 
as it does that the Scandinavian iee did reach the mainland of 
Scotland, and would therefore be sufficiently strong to deflect the 
easterly flows of the Highland ice in this district, in part at any rate, 
in a southerly direction, and thus probably accounted for the trans- 
port of the Buchan Ness and Peterhead rocks to Cambridgeshire. 
The quartz-porphyry recorded from so many localities, not, 
however, including the Travellers’ Rest, by Rastall and Romanes, 
and referred to by them as porphyry “‘z”’, has now been identified 
as being a Scottish type, where it is of fairly wide distribution, being 
1 GroL. Maa., vol. lvii, 1920, p. 522. 
a 
