IGNEOUS GEOLOGY OF THE BATHGATE AND LINLITHGOW HILLS. 365. 
The Dykeneuk and Castlecary Limestones. 
The Dykeneuk limestone, though proved in many bores, is seen at the surface in 
three exposures only—at Dykeneuk, Woodcockdale, and Carribber. The Castlecary 
or Levenseat limestone is exposed at Craigenbuck, at the Birkhill viaduct, the Avon 
aqueduct, Carribber, Bowden Hill, and Lochcote, Both limestones are probably con- 
tinuous across Bowden Hill, though in places cut out by intrusive rock. South of 
Bishopbrae their presence beneath the surface has been repeatedly proved in bores. 
The strata between the two limestones consist of sandstones and shales, thickest towards 
the north and thinning out towards the south, with the effect of bringing the limestones 
closer together from Carribber southwards. No trace of volcanic activity is found 
above the Dykeneuk limestone. 
The Volcanic Necks. 
These are found in the eastern part only of the volcanic area. A small neck full 
of green ash pierces the Riccarton Hills south-east of Beleraigs. Another, full of coarse 
agelomerate, breaks through the stratified ash of the first volcanic zone to the west of 
Wester Ochiltree. A group of seven small necks is found in the neighbourhood of 
Hiltly and Parkly Place, some filled with coarse agglomerate, and others with fine- 
grained ash similar to that at the base of the third volcanic zone. The Necks of 
Pilgrim’s Hill and Carriden are also included in the accompanying map. 
The Intrusive Rocks. 
The intrusive rocks of this district are readily separated into two groups according 
to their microscopical characters,—a smaller group of olivine-basalts and dolerites, and a 
larger group of augite diabases, with little or no olivine, but with frequently abundant 
hypersthene. An intersertal microlitic or micropegmatitic groundmass is usually present 
in the latter, in greater or less abundance. ‘This difference in mineral composition 
seems to be most easily explained on the assumption that the two groups are the 
products of different periods of igneous activity. The smaller and more basic group 
might readily have been produced from the consolidation of igneous material similar to 
that which produced the lavas. They may therefore be regarded as more or less 
contemporaneous intrusions. The large group, however, is of a more acid character, 
and is certainly the product of a later period of igneous activity. 
(a) Contemporaneous intrusions.—Small intrusions of olivine-basalt are found in 
many of the Necks enumerated above, but, other than these, few contemporaneous intru- 
sions have been recognised throughout the volcanic zones. A small intrusion of olivine- 
basalt cuts the ash of the first voleanic zone in the Brox Burn near the Bangour 
reservoir. A short dyke of similar material occurs in the third volcanic zone north- 
