fome Strata in Ireland and Scotland. 
97 
in appearance to that before deicribed. In its vicinity the chert 
is extremely broken and cellular; and I am of opinion, that 
this is a continuation of the Gartnefs Whyn Dyke, it having 
the fame range, and nearly the fame breadth. After viewing 
the Fort (fee Pennant’s Voyage in 1772, p. 219.), we be- 
gan our examination of the fubftances which compofe the hill. 
They are in general filiceous, varioufly blended ; the northern 
brow is of chert, the joints of which range E. and W. and 
the beds are in fome parts vertical, in others horizontal. Here 
is an irregular bed of iron ore, called emery by the inhabi- 
tants ; it is from fix to twelve inches in thicknefs, and may be 
traced about four fathoms in length. Above it is a flrange 
mixture of chert, hornftone, and friable yellow fand-ftone, 
blended together without any order or regularity. This bed of 
iron ore is vifible on the S.W. part of the hill, where it is 
near two feet thick, is ftratified with the chert, which lies in 
beds from three inches to two feet in thicknefs, and is covered 
with a cryftalline fand. On the fouth fide of the hill, where 
a trial has formerly been made for iron ore, there are feveral 
lumps collected in an heap, but no appearance of bed or vein. 
Where the rock has been laid bare, it is an hard chert, with 
an outer coat of foft yellow fand-ftone. Higher up the hill is 
an hard chert, with a kind of bladder®holes. Skirting the 
hill we defcended on the north fide, and faw two places, for- 
merly wrought, where there is not any appearance of a vein, 
but merely a jumble of iron pyrites. At a very fmall diftance 
from hence, the limeftone fhews itfelf, and trials have been 
made for lead ore. Having furrounded the hill, and examined 
it attentively, and having feen the chert, of which it is chiefly 
compofed, thrown into an infinite variety of forms ; in fome 
parts broken and indented, with a kind of empty bladder- 
O 
holes ; 
