fame Strata in Ireland and Scotland. 85 
difcovered a Whyn Dyke, or vein of lava% about two feet 
wide, included in a vertical fiflure ranging S.B. by E. and 
N.W. bv W. Going round to the oppofite fide of the bay, 
we found the lava on the cliff ranging as above; but the vein, 
or Whyn Dyke, much fmaller, being only from eight to ten 
inches between the granite fides, which feemed to continue 
doling ; nor could it be feen on the main land of Mull, which 
was at no great diftance. The fiflure, which includes the lava* 
is, where firft difcovered, wider than the vein of lava it contains,, 
which therefore Hands wholly detached from the SfW. fide. 
The lava and fiflure range quite through the point; and to 
the N.W. by W, on the oppofite fide of a fmall found or 
inlet, it appears on a rocky ifland, divided into two veins,, ftilli 
keeping nearly the fame direftion. 
About fix yards to the weftward of the lava vein, or Whyn 
Dyke, is an i m men fe fiflure in the granite, ranging N. by W* 
and S. by E. It is from nine to ten feet wide, and, by efti- 
mation, about an hundred and twenty feet deep. At the 
northern extremity, near the top, two ftones are fufpended in 
a moft extraordinary manner between the fides : the under one 
is fixed, and upon that the other appears to lie loofe. (See fig*. 
There is a large cavern m the weftern fide of the fiflure^ 
and a correfponding fiflure is ieen on the oppofite Chore* 
In the evening, when the tide favoured us, we failed. The 
night proved calm and foggy, and in the morning we found our- 
felves near the weft coaft of Jura, to the northward of Loch 
Tarbut. As we approached the Chore, we found it rocky for the 
diftance of a quarter of a mile from the cliffs, which are low, and 
apparently of chert. Being quite calm, we rowed along fhore^ 
# See Magellan’s Cronftedt, p. 916, 
pafled 
