673 
of the millstone-grit, as indicated by the drift-bedding over 
a district twenty-five miles long in South Yorkshire and 
North Derbyshire, and I find that on an average the current 
was from the north-east. This also agrees with the direction 
in which the sandstone beds become thicker and of coarser 
grain ; and altogether the fact of the materials having been 
drifted from the north-east, in my opinion, admits of no doubt 
whatever. If such be the case, the land whose waste 
supplied the material must be looked for in some such 
direction ; and I now proceed to consider what kind of 
rocks it was composed of. 
The only way in which this can be done is to examine 
the pebbles found in the grit-stone, which are as it were 
specimens of the rocks of that country preserved for our 
inspection. As previously remarked, by far the commonest 
pebbles are of quartz, like that forming one of the con- 
stituents of coarse-grained granites ; but a considerable 
quantity are evidently portions of various yellow, pink, grey, 
and almost black quartz-rocks or quartz-schists. There are 
also many pebbles of white or brownish orthoclase felspar, 
similar to that in coarse-grained granites, and it therefore 
becomes interesting to ascertain for certain whether some of 
the quartz and this felspar did not originally constitute a 
granitic rock. After much careful search I have at length 
obtained extremely good proof of this fact, for I have 
found a few pebbles of undoubted granite, some of which 
are composed of a union of quartz and felspar, like a coarse- 
grained granite, which are in every respect similar to the 
quartz and felspar, so abundant as pebbles of each mineral 
alone. Besides such crystalline felspar there occur pebbles 
of a fine-grained felspathic rock, with a few laminse of mica ; 
and, though usually much decomposed, it appears to have 
been some kind of eurite. I have also found one pebble 
of a moderately fine and even-grained rock, much like some 
varieties of green stone, or a fine-grained syenite, consisting 
E E E 
