fome Strata in Ireland and Scotland. jg 
About a-quarter of a mile from the fpot where the bearings 
were taken, is a deep glen,' running N.N.E. to the fea. It is 
about* thirty yards in length, and twenty in breadth. The 
flrata are diipofed in the following extraordinary manner. The 
uppermoft is ten yards of lava, with horizontal divifions and 
vertical joints, taking the form of rude pillars. Under this is 
an horizontal bed of a perfectly vitrified fubftance, which ap- 
pears to have been a fihale, and is from one to two inches in 
thicknefs. Beneath this, is about three yards of a filiceous 
gravelly concrete ; below which are horizontal beds of indu- 
rated marl, of various thickneftes, from fix to twelve inches. 
The whole of thefe beds, taken together, are about four yards, 
and there is a large fiffure in them, on the weft fide of the glen. 
Laftly, are ten yards of rude lava, containing fpecks of quartz 
and mica unaltered, pieces apparently of granite, and fome 
nodules of calcined chert. The whole is incumbent on regular 
bafalt pillars, of various dimenfions, from eighteen to fix 
inches diameter, varying in the number of their fides, fome 
having five, fome fix, and others feven fides. They are alfo 
as varioufly difpofed ; thofe on the weftern extremity of the 
glen being ftraight, and lying horizontally ; whilft of thofe 
on the eaft fide fome are bare, and ftanding perpendicularly ; 
and others, which are furmounted by the rude lava, are in- 
clined and curved, as if they had taken that form in cooling 
from the preffure of the incumbent weight. See Tab. IV. fig. i. 
Many of the pillars are very full of bladder- holes ; the articu- 
lations of the joints are clofe, though not fo clofe as thofe of 
the Giant’s Caufeway ; but, like thofe, their tops, where ex- 
pofed, are either concave or convex. 
At the extremity of the glen is an infulated rock, fupported 
by bafalt pillars (fig. 2.), which are fomewhat curved and 
inclined. 
