CHAPTER XXXVII 
THE SEVERAL BASALT-PLATEAUX AND THEIR GEOLOGICAL HISTORY, 
ANTRIM, MULL, MORVEN AND AEDNAMUECHAN 
There are five districts in North-western Europe where the original wide- 
spread Tertiary lava-fields have been less extensively eroded than elsewhere, or 
at least where they have survived in larger and thicker masses. Whether or 
not each of them was an isolated area of volcanic activity cannot now be 
determined. Their several outflows of lava within the area of the British 
Isles may have united into one continuous volcanic tract, and their present 
isolation there may be due entirely to subterranean movements and denuda- 
tion. There is a certain convenience, however, in treating the districts' 
separately. They are — 1. Antrim; 2. Mull, Morven and Ardnamurehan ; 
3. Small Isles; 4. Skye; 5. The Faroe Islands. 
i. ANTRIM 1 
The largest of the basalt-plateaux of Britain is that which forms so 
prominent a feature in the scenery and geology of the North of Ireland, 
stretching from Lough Foyle to Belfast Lough, and from Ratlilin Island to 
beyond the southern margin of Lough Neagh. Its area may be roughly 
computed at about 2000 square miles. But, as its truncated strata rise 
high along its borders, and look far over the surrounding low grounds, it 
must be regarded as a mere fragment of the original volcanic plain. It 
may be described as an undulating tableland, which almost everywhere 
terminates in a range of bold cliffs, but which, towards the centre and 
south, sinks gently into the basin of Lough Neagh. The marginal line of 
escarpment, however, presents considerable irregularity both in height and 
form, besides being liable to frequent local interruptions. It is highest on 
the west side, one of its crests reaching at Mullaghmore, in County 
Londonderry, a height of 1825 feet. It sinks down into the valley 
of the Bann, east of which it gradually ascends, forming the well-known 
range of cliffs from the Giant’s Causeway and Bengore Head to Ballycastle. 
1 The basalts of Antrim are the subject of an abundant literature. I may refer particularly 
to the papers of Berger and Conybeare (Trans. Geol. Soc. iii.), the Geological Report of Portlock, 
and the Explanations of the Sheets of the Geological Survey of Ireland. Other papers will be 
afterwards cited. The general features of the Antrim plateau are shown on Map VII. 
