546 
ELEMENTS OF GEOLOGY. 
stone, shale, and iron-stone of the lower coal-measnres, and, 
on the East Lomond, with Mountain Limestone. I examined 
these trap-rocks in 1838, in the clitFs south of St. Andrews, 
where they consist in great part of stratified tuffs, which are 
curved, vertical, and contorted, like the associated coal-meas¬ 
ures. In the tuff I found fragments of carboniferous shale 
and limestone, and intersecting veins of greenstone. 
Fife—Flisk Dike ,—A trap dike was pointed out to me by 
Dr. Fleming, in the parish of Flisk, in the northern part of 
the county of Fife, which cuts through the gray sandstone 
and shale, forming the lowest part of the Old Red Sandstone, 
but which may probably be of carboniferous date. It may 
be traced for many miles, passing through the amygdaloidal 
and other traps of the hill called Norman’s Law in that par¬ 
ish. In its course it affords a good exemplification of the 
passage from the trappean into the plutonic, or highly crys¬ 
talline texture. Professor Gustavus Rose, to whom I sub¬ 
mitted specimens of this dike, found it to be dolerite, and 
composed of greenish black augite and Labrador feldspar, 
the latter being the most abundant ingredient. A small 
quantity of magnetic iron, perhaps titaniferous, is also pres¬ 
ent. The result of this analysis is interesting, because both 
the ancient and modern lavas of Etna consist in like manner 
of augite, Labradorite, and titaniferous iron. 
Erect Trees buried in Volcanic Ash at Arran .—An inter¬ 
esting discovery was made in 1867 by Mr. E. A. Wtinsch in 
the carboniferous strata of the north-eastern part of the isl¬ 
and of Arran. In the sea-cliff about five miles north of Cor- 
rie, near the village of Laggan, strata of volcanic ash occur, 
forming a solid rock cemented by carbonate of lime and en¬ 
veloping trunks of trees, determined by Mr. Binney to belong 
to the genera Sigillaria and Lepidodendron. Some of these . 
trees are at right angles to the planes of stratification, while 
others are prostrate and accoiiipanied by leaves and fruits 
of the same genera. I visited the spot in company with Mr. 
Wiinsch in 1870, and saw that the trees with their roots, of 
which about fourteen had been observed, occur at two dis¬ 
tinct levels in volcanic tuffs parallel to each other, and in¬ 
clined at an angle of about 40°, having between them beds 
of shale and coaly matter seven feet thick. It is evident 
that the trees were overwhelmed by a shower of ashes from 
some neighboring volcanic vent, as Pompeii was buried by 
matter ejected from Vesuvius. The trunks, several of them 
from three to five feet in circumference, remained with their 
Stigmarian roots spreading through the stratum below, which 
had served as a soil. The trees must have continued for 
