18 
J. R. Dakgns — Glacial Origin of Terraces. 
Sheet . 1 This paper will doubtless call forth a number of equally 
elaborate answers : and this is well. But if Mr. Goodchild has a 
fine goose fattened on the Limestone terraces of Wensleydale, I have 
an equally fine gander reared on Gritstone terraces in Derbyshire : 
and if a frozen sauce of regelated snow from wintry storms of the 
Great Ice Age is good for one, it is equally good for the other. 
Dropping metaphor, there is no difference between terraces, mainly 
of limestone, in Wensleydale, and other terraces, chiefly of grit, that 
are found over all the Millstone Grit area of South Yorkshire and 
Derbysliire, saving that while limestone predominates in the one, 
beds of grit do in the other. If an ice-sheet carved out the terraces 
of the Limestone Dales, it equally did tliose of the rest of Yorkshire, 
Derbyshire, and, may I not add, of Cheshire and Staffordshire ; yet 
no sober-minded man, looking at these terraces, over so large an area, 
rising and falling with every chauge in the inclination of the beds, 
but ever following the dip and keeping to the bedding-planes, could 
possibly suppose that they were carved out b} r ice-sheets. What in 
the name of reason is to cause a great grinding ice-sheet, of whose 
vaunted powers we have heard so much of late, to keep to a bedding- 
plane ; much more to rise and fall with the dip of the beds? Add 
to this all-suffieient objection to Mr. Goodchild’s theoiy the fact that 
over a great portion of this terraced area there is not a particle of 
drift or a single ice-scratch, that has yet been discovered, to bear 
witness to the fact of any ice-sheet having been there at all. 
The fact that the terraces conform to the bedding is to my mind 
conclusive against the Glacial Erosion theory ; but, as Mr. Goodchild 
actually thinks this an argument in favour of his theory, allow me 
to ask him how he reconciles this accommodation of glacial action to 
differences of hardness with the power of ice to smooth and round 
off gnarled crystalline rocks, or to scoop out rock-basius in tough 
Silurian slates quite irrespective of degrees of hardness. It seems 
quite clear that ice cannot behave at one and the same time in such 
opposite ways ; if it is guided in its course by such differences of 
hardness as occur between limestone and sandstone, or these and 
shale, it cannot scoop out rock-basins in total disregard of such 
differences ; and if it can scoop out such rock-basins, it will not be 
so affected in its course as to carve out bedding terraces. 
As for the lines of swallow-holes along the junction of the lime- 
stone with the overlying shale, the fact that these exist only along 
this line of junction, and are not equally to be found over the bare 
surface of the limestone, is no argument against the shale bank 
having been eaten back by ordinary atmospheric agencies ; for it is 
just to the very presence of the shale that the marked lines of 
swallow-holes owe their existence ; the actual hole in the limestone 
is generally a very insignificant matter, mostly a mere ordinary 
joint. The marked swallow-holes are in the shale itself, and are due 
to the soft shale crumbling away and falling into the open joints 
below, and so giving rise to a funnel-shaped hollow much wider at 
1 “ Glacial Erosion,” by J. G. Goodchild, Geol. Mag., July, 1875, Dcc. II. 
Vol. II. p. 323. 
