26 Hugh Miller — Escarpments and Terraces, 



under the latter it stands foremost, as it accordingly does in featural 

 prominence. 



3. Collateral Difficulties. — The regularity with which the terraces 

 extend along the Dale sides and their correspondence on opposite 

 slopes. — Their perfection at considerable heights up the sides. — The 

 persistence with which they follow a disturbed bed " through all its 

 variations of position and inclination." 



Most of these points apply with equal force to the Northumber- 

 land district of Yoredale rocks which has come under my observa- 

 tion, thus affording an additional proof of the identity of the phe- 

 nomena in the two districts. But in Northumberland they are 

 attended by a sufficiency of convincing proofs that the escarpments 

 — terraced or otherwise — are of pre-glacial origin, and by an expla- 

 nation of most of the difficulties I have — correctly, as I trust— sum- 

 marized. To state these in detail is the object of this communication, 

 in which I am perforce more local and special than Mr. Goodchild 

 found it necessary to be. 



1. Proofs of the Pre-Glacial Age of the Escarpments Afforded hy their 

 Belations to the Drainage. — The general relations of the drainage 

 system to the ranked lines of escarpments among which it ramifies 

 strongly suggest their pre-glacial origin. Evidently no high barrier- 

 ridges existed, to coerce the waterflow along single lines, or to pond 

 it by sudden obstructions. There is, it is true, a tendency to prefer 

 the intermediate hollows, as if the present configuration had been 

 faintly marked out — though in a degree perhaps only appreciable to 

 the unerring selection of water — when channels were first sought. 

 But it is the larger gradient — that to which the summit lines of the 

 escarpments themselves give the index — that determines the general 

 direction of flow ; and between the stream crossing the ridges at right 

 angles and almost ignoring their presence, yet occasionally deflected 

 along a furrow, and that occupying single grooves for long distances 

 but now and then shunting, as it were, its line of flow, there is a 

 graduating series of zig-zag courses, in which the furrow line tends 

 more and more to subtract from the gap one. This a priori proba- 

 bility is well borne out. 1st. There is no evidence that the stream 

 waters were dammed back by the escarpments now breached. 2nd. 

 Streams are found to strike across escarpments at points where — 

 closing the gap — their course was free elsewhere. 3rd. Occasion- 

 ally a transverse gap contains a glacial deposit or gives other 

 evidence of its pre-glacial origin. 



A single stream affords most of these proofs, that, namely, which, 

 after entering and threading a portion of the tract of typical escarp- 

 ment development, j^asses by the village of Simondburn on its way 

 to the North Tyne. The first good escarpment encountered by it is 

 of sandstone, and above the average height. The sides of the gap 

 slope at about 20°, and converge pretty directly upon the stream, 

 like the limbs of a V towards a blunted apex. The height (about 

 60 feet) is sufficient to cause no mean lakelet, yet neither basin nor 

 peat-moss (of which there are numbers in the neighbourhood) fronts 

 the gap, nor do the stream sides expose lacustrine deposits : 10 or 



