CH. XXVII 
CONNECTION OF PUYS WITH THE BEDDED LAVAS 
435 
not yet proceetled so far as to isolate the column of agglomerate or tuff from 
the sheets of tuff that were strewn around the old volcano. In such eases, the 
actual limits of the vent are still more or less concealed, or at least no sharp 
line can he drawn between the vent and its ejections. As an illustration 
of this connection of a volcanic p)ipe with the materials ejected from it over 
the surrouneling country I would cite Saline Hill 
in the west of Fife. That eminence rises to a 
height of 1178 feel above the sea, out of a band 
of tuff which can be traced across the country 
for fully three miles. Numerous sections in tlie 
water -courses show that this tuff is regularly 
interbedded in the Carboniferous Limestone series, 
so that the relative geoh)gical date of its eruption 
can be precisely fixed. (In the sontli of Saline 
Hill, coal and ironstone, worked under the tuff, 
prove that this p)ortion of the mass belongs to 
the general sheet of loose ashes and dust, extend- 
ing outwards from the original cone over the floor 
(.11 the sheet of water in which the Carboniferous 
Limestone series of strata was being deposited. 
But the central portion of the hill is occupied 
by one or more volcanic pipes. A section across 
the eminence from north-west to south-east would 
probably show the structure represented in Fig. 
148. Immediately to the east of the Saline Hill 
lies another eminence, known as the Knock Hill, 
which marks the site of another eruptive vent. 
A coal-seam (the Little Parrot or Gas Coal) is 
worked along its southern base, and is found to 
plunge down steeply towards the volcanic rocks. 
This seam, however, is not the same as that worked 
under the Saline Hill, but lies some 600 feet below 
it. Probably the whole of the Knock Hill occupies 
the place of a former vent. 
A further stage of decay and denudation brings 
before us the entire severance of the volcanic 
column from the materials that were ejected from 
it. An excellent example of this isolation of the 
neck in the midst of surrounding masses of tuff 
and lava which proceeded from it is presented by 
the Binn of Burntisland, to which I have already 
alluded. A section across that eminence gives 
represented in Fig. 149. The dip of the rocks 
pipe at this locality has been j)rodnced long after 
had ceased. The arch here shown is really the prolongation and final dis 
appearance of the great anticlinal fold of which the Pentland Hills form the 
the geological structure 
away from the volcanic 
the volcanic Ydieuomena 
