218 JS. Flett & H. H. Read— 
pebbles and clay and affords excellent sections, which give a very 
satisfactory idea of the composition and structure of the deposit. 
The working face of this pit is at present 8 feet high, and a small 
excavation in the floor of the pit reveals another foot or two of 
greyish-white sandy clay with pebbles. The base of the deposit 
is not anywhere exposed, and the thickness is consequently not 
known, but is presumably not less than 8 or 10 feet at this place. 
The largest pebbles are about a foot in diameter, but the majority 
are from 2 to 5inches. Most of them are very well rounded, and the 
whole deposit gives the impression that the pebbles have suffered 
much attrition and resemble those found on a sea-beach where 
wave action has been long continued. Quite nine-tenths of the 
pebbles are quartzite, of a very fine and pure variety, and all these 
are perfectly waterworn and rounded. The quartzites are by no 
means uniform in character. Most are fine-grained, granular or 
granulitic when examined with the lens, and contain very little 
felspar or mica. Others, however, have white mica flakes in thin 
shimmering films, and might be described as very fine-grained 
white quartz-schists. Still others have a more crystalline appearance, 
with large areas of clear glassy transparent quartz ; no other minerals 
can be seen in the hand specimen. 
Taking the quartzites as a whole, we may say that they have well- 
defined characters, which are: (a) their white colour; (b) their 
great purity ; (c) their highly metamorphic and crystalline texture. 
They are certainly not derived from the local rocks, which, as already 
said, are Macduff Slates and Old Red Sandstone, and, furthermore, 
there are no known Aberdeenshire or Banfishire quartzites from 
which it seems possible they could have been’derived. The Durn 
Hill and Cullen quartzites of Banffshire contain usually biotite and 
orthoclase, which give them a yellowish or pinkish colour when they 
are weathered. The quartzite and pebbly grit bands of the Macduff 
Slates are even more impure. Quartz veins are not common in 
N.E, Scotland, and most of the Delgaty pebbles are not derived 
from quartz veins. Altogether their origin is a problem on which 
little light has been thrown by the investigations of the geologists 
who have studied the rocks of the Hastern Highlands. Their 
lithological characters, however, are so well marked that it is 
seldom difficult to identify one of these pebbles in any of the 
superficial deposits of the district. 
Less than one-tenth of the pebbles are flint, and these have the 
general character of flint pebbles wherever met with. They range up 
to 9 inches in diameter, and it is not seldom apparent that they are 
less perfectly rounded than the quartzites, though many of 
them are extremely waterworn. The flint is soft and brittle and ~ 
cracks readily under the hammer; the broken faces have often a 
dull or waxy lustre; pure black flint is practically never seen, but 
grey, brown, red, and greenish colours are prevalent. Often the 
flints have a thick dull rind, which is grey or white, and sometimes 
