464 PROFESSOR GEIKIE ON THE 
eround plan represents this structure as seen in the neck which forms the 
headland at the harbour. Alternations of coarse and fine tuff with bands of 
coarse agglomerate, dipping at angles of 60° and 
upwards, may be traced round about half of the 
circle. The incomplete part may have been 
destroyed by the formation of another contiguous 
neck immediately to the east. To the west of 
Earlsferry another large, but also imperfect, circle 
may be traced in one of the shore necks. A 
Fig, 7.—Ground-plan of Voleanic Neck, Quarter of a mile further west rises the great 
Bhe Harbour, showing circular deposition cliff-line of Kincraig, where a large neck has been ] 
_'T, Tuff of the neck, the arrows showing Cut open into a range of precipices 200 feet high, 
its Inward ip, BB, Dkes, 8. Smad" as well as by a tide-washed platform more than 
has beenyopaned. half a mile long. The inward dip and high angles’ 
of the tuff are admirably laid bare along that portion of the coast line. The 
section in which almost every bed can be seen, and where, therefore, there is 
no need for hypothetical restoration, is as shown in fig. 8. 
s 
A 
SO 
B 
wee 
Fig. 8.—Section across the great vent of Kincraig, Elie, on a true scale, vertical and horizontal, 
of six inches to a mile. 
1, Sandstones, shale, &c., of Lower Carboniferous age, plunging down toward the neck T ; B, columnar basalt. 
I have already referred to the frequently abundant pieces of stratified tuff, 
found as ejected blocks in vents filled with tuff, and to the derivation of these 
blocks from tuff originally deposited within the crater. There can, I think, be 
little hesitation in regarding the stratification of these Fife vents as exhibitions of 
this same operation. The general dip inwards from the outer rim of the vent 
strikingly recalls that of some modern volcanoes. By way of illustration, I give 
here a section of part of the outer rim of the crater of the Island of Volcano, 
sketched by myself in ascending the 
mountain from the north side (fig. 9). 
The crater wall at this point consists 
of two distinct parts,—an older tuff 
(a), which may have been in great 
measure cleared out of the crater 
before the ejection of this newer 
tuff (>). The latter lies on the 
outer slope of the cone at the usual angle of 30°. It folds over the crest 
Fig. 9.—Section of part of crater rim, Island of Volcano. 
