iby On the Origin of “ The Scalp.” 
of the entrance to the ravine near the School-house ; and yet no 
one who is conversant with the forms of river valleys can doubt 
that “The Scalp” has been formed by river action, and that a 
considerable stream, somewhat proportionate to the size and depth 
of the ravine, originally flowed through it. 
In the following observations, therefore, I must assume that 
the Scalp is the channel of a river which once flowed through it, 
and that it has been scooped out by river action. If anyone 
denies this, I ask him to explain its formation by any other 
hypcthesis consistent with observed physical facts. The Scalp is 
certainly not due to a “ gaping fissure” in the rocks, or to a fault or 
a fracture, as the schists pass across from side to side with perfect 
regularity, as shown by the Geological Survey Map (Sheet 121) ; 
besides, geologists are agreed that it is altogether unphilosophical 
to call in the hypothesis of gaping fissures in order to explain 
such features as that here referred to. 
I assume then that the Scalp is an old river-valley, and the 
question arises;—What has become of the river which once rolled 
through it? for assuredly the little driblet of a foot or two in 
width which runs by the road-side cannot be considered as the 
sculpturing agent in this work, if we suppose that there is any 
proportion between the work done and the agent—between the 
river-valley and the river which has made it. 
The answer to the above question, as it appears to me, is to be 
sought in the restoration of the original stratification of the 
country. From several considerations we have reason to believe, 
that the granitic and schistose rocks of the Dublin and Wicklow 
range formed a ridge in the seain which the Carboniferous strata 
were deposited. Fragments of granite have been found imbedded 
in the limestone itself in the neighbourhood of Dublin, proving 
that the granitic ridge was in existence, probably rising in places 
from beneath the Carboniferous sea with a shelving shore, which 
sea itself stretched far way northwards and westwards. The 
Upper and Middle Carboniferous strata were originally deposited 
wherever the limestone itself was formed, so that the great 
central plain of Ireland was in all probability the seat of a wide- 
spread coal-formation, which has since been swept away by 
denudation with the exception of a few little patches, such as 
those of the Kilkenny and Slieveardagh coal-fields, which have 
