492 H. J. EUNSON ON THE RANGE OF THE 
and the one at Gayton. The base of the clay at Orton is 292 feet 
below sea-level, as compared with 299 feet at Gayton, a difference 
of only 7 feet, the distance between the two sites being 16 miles ; 
the White-Lias limestone is present at both places, but we have no 
mention of it in either of the two earlier investigations, nor was it 
found at the Kettering-road boring*; the green shale is very 
similar, but absent in the three other borings. At Orton no trace 
of Trias is found; the black shales and bone-beds are also wanting. 
The thick bed of white sandstone, probably a local deposit, was 
followed by a breccia. This breccia contained fragments of quartz- 
andesite and also of quartz-feisite, the rock found immediately below 
and upon the eroded surface of which it rested. The quartz-felsite 
was proved toa depth of 74 feet, and in it, at 789 feet, the boring 
was stopped. 
This rock was examined by Prof. Bonney ; he remarked :—“ This 
rock is a quartz-felsite, specks of quartz and crystals of whitish 
felspar about 0-1 inch long appearing in a very compact greyish 
matrix. This is traversed by very numerous minute cracks, which 
appear to be filled by a paler mineral. A distinct cleavage is 
exhibited, the planes, whose surfaces are slightly irregular, making 
an angle of about 18° with the axis of the core. Under the micro- 
scope the rock exhibits a rather indistinct devitrified structure, 
which in many parts is marked by the above-mentioned cracks, and 
subsequently formed minerals. I do not see any distinct mdication 
of perlitic, fluidal, or spherulitic structure, but I believe the rock 
has once been a glassy rhyolite, and has been subsequently devitrified 
and crushed, whether simultaneously or not I cannot say. The 
usual filmy, almost colourless mineral (which extinguishes at rather 
small angles, some 10°, with the vibration-planes of the crossed 
nicols, and shows a sort of golden tint most brightly at between 
50° and 60°) occupies, or to some extent “solders up,” the cracks. 
There are also numerous granules of ferrite and occasional dark 
lines of an iron-oxide, which, i think, have occupied cracks. There 
are several grains of rather clear quartz, and crystals of felspar, 
orthoclase, and plagioclase, both rather decomposed. The quartz is 
cracked, the felspar still more broken. There are many microliths 
which I cannot certainly identify, but some, I think, are apatite, 
and perhaps there is a little mica.” 
In the opinion of Prof. Bonney this rock is very similar to that 
found at High Sharpley, in Lincolnshire, which he has described? as 
either “an altered rhyolitic tuff or a true rhyolite much crushed ;” 
and he has little doubt that it is a member of the same series as the 
voleanic group of Charnwood Forest. 
It is interesting to note the extension of this group so far south- 
ward as Northamptonshire, some 25 miles to the south-east of the 
Charnwood area, and which most probably, during the later Car- 
* These three borings are situated between Orton and Gayton. 
+ Quart. Journ. Geol. Soc. vol. xxxvi. p. 342. 
