242 
STATHER : XOTES OX EAST YORKSHIRE BOULDERS. 
It will be seen from Table II. that, although the Car- 
boniferous limestones and sandstones, and the basalts, have 
travelled into our district from practically the same area, the 
relative proportions of the boulders from the two groups vary- 
considerably from point to point. Thus, while it is probable 
both groups decrease numerically southwards, the percentages 
show that the basaltic group increases relatively from Saltburn 
southwards. The explanation of this seems to be that the large 
boulders of basalt l^ear transport better than similar masses from 
the Carboniferous sedimentary rocks. 
In south Holderness the Magnesian Limestone (group 3) 
is rarely found excepting as pebbles, but these grow in number 
and size northwards. Large boulders begin to appear north of 
Scarborough, and at Whitby and Saltburn, as the table shows, 
they form from 5 to 7 per cent, of the non-local boulders present 
in the clays. This rock is matched by the Magnesian Lime- 
stone found in situ at Roker, near Sunderland. 
We now come to the boulders of igneous rocks included 
in group 4, which are shown by the table to decrease both 
numerically and proportionately northwards. This northward 
decrease is all the more noteworthy when we remember that 
boulders of Sliap granite and other Lake District rocks, and of 
the Cheviot porphyrites, all included in this group, increase 
rapidl}'- in the same direction. This seeming anomaly arises, 
I think, from the influence of the boulders from Scandinavia. 
Among the boulders of south Holderness occur very commonly 
types which agree with certain Scandinavian rocks ; the best 
known of these being the augite-syenite {laiirvikite) and the 
rhomb-porphyry. These types, although not by any means un- 
known in the drifts of North Yorkshire, are much rarer there 
than in the south. For instance, at Dimlington, in south 
Holderness, we should find at least one hundred boulders of the 
above-named Scandinavian rocks to one of Shap granite, while 
on the other hand at Robin Hood's Bay or Runsv*^ick Bay (both 
near Whitby) the Shap boulders outnumber the Norsemen b}^ 
twent}' to one. Seeing then that tlie boulders of group 4 
