362 MR J. D. FALCONER ON THE 
Carsie Hill, east of Cauldhame, and at Peat Hill, on the north side of the Haugh 
Burn fault. 
The Third Voleanie Zone, or The Kirkton and Hillhouse Lavas. 
This zone includes the Kirkton, Tartraven, and. Hillhouse lavas. A very charac- 
teristic ash, with black matrix and yellow lapilli, lies in several places at the base of 
this zone. It is well seen at Whitelaw, Craigs, Whitebaulks, and Hillhouse. The 
lavas of this zone can be studied with ease in numerous exposures from Kirkton Mains 
and Boghall to The Knock. Porphyritic olivine-basalts predominate, but a thin 
band of dolerites strikes N.W. from the Raven Craig. The limestones and accom- 
panying shales and ash of the east and west Kirkton quarries, so well described in 
the Survey Memoir accompanying sheet 32, occur as isolated lenticular patches 
between successive lava-flows, and evidently occupy a much higher horizon than the 
Tartraven Limestone. A similar intercalation of sandstone may be seen on the eastern 
slope of the Knock Hill. From the Knock to Tartraven little rock is visible, but 
numerous exposures are found in the Tartraven Hills where the road cuts through a 
series of dark-blue lustrous limburgitic olivine-basalts. The lavas of this zone probably 
run out to the north of the Mains Burn, for in a streamlet to the east of Balvormie 
the only representative of the zone is the basal ash noted above. This apparently 
swells out by Whitebaulks to Hillhouse, where it dips below a group of coarse-grained 
olivine-dolerites, which, after suffering displacement by the Haugh Burn fault, runs out ; 
to the north of Parkly Place. 
The Hurlet Limestone. 
This well-marked horizon can be traced from Glenbare quarry, east of Bathgate, to 
the North Mine quarry on the Tartraven road. For a mile to the north of this point 
the outcrop is conjectural, no trace of the limestone being found at the surface. It 
reappears, however, in characteristic sections in the Hillhouse and MHiltly quarries. 
North of Hiltly the outcrop must be shifted to the east by the Haugh Burn fault, and 
probably strikes north from the vicinity of Parkly Place to Linlithgow Poorhouse, and 
thence north-west to the shore at Stacks. The Hurlet Limestone is throughout — 
associated with sandstones, shales, and thin ashbeds; and detailed descriptions of 
sections, formerly better visible than now, may be found in the Survey Memoirs and 
Mr CanbELt’s papers. 
To the east of Linlithgow no volcanic rocks are found below the Hurlet Limestone, — 
within the limits of the present map, and, other than the thick sandstone formerly 
quarried at Kingscavil, little rock of any kind is visible. 
The Fourth Voleante Zone, or The Hilderston and Hiltly Lavas. 
This zone reaches its greatest thickness immediately to the south of Linlithgow, 
but even here the apparent thickness is greater than the actual thickness, on account of © 
