W.S. Gresley— Variegated Coal-measures. 115 
depth of 15,000 feet at a gradient of about 34; to =, the compara- 
tively low results in the case of Chile being due to the narrowness 
of the mountain range, 30 miles in mean breadth, as compared with 
300 miles in the case of Bolivia. 
The above results, which are probably rather under than over 
estimates, fall considerably short of those to be drawn from Suess 
and Fischer’s formula, but are probably much in excess of the views 
held by British physical geographers generally ; and the conclusion 
was drawn, that if the same processes of reasoning and calculation 
were applied to all parts of the world, it would be found that the 
ocean waters are piled up to a greater or less extent all along our 
continental coasts, producing very important alterations in the ter- 
restrial configuration as compared with an imaginary ellipsoidal, or 
geodetic, surface, to which all these changes of level must necessarily 
be referred. 
VI.—Tue OccurreNcE oF VARIEGATED CoaAt-MEASURES, ALTERED 
TRONSTONES, ETC., AT SwWADLINCOTE, DERBYSHIRE. 
By W. S. Gresuzy, F.G.S. 
HIGHLY interesting and remarkable instance of altered Coal- 
measures, due to impregnation by hydrous and anhydrous 
oxides of iron, infiltrated by water from the overlying Permian 
strata, can now be seen in situ in the Ashby-de-la-Zouch Coal-field, 
and I think it should be made known in order that those who may 
wish to study such phenomena may have the opportunity of doing 
so. The following is a general description of the section. 
The section may be seen near the Fire-brick and Pipe Works of 
Messrs. Wragge, at Swadlincote, near Burton-on-Trent. The exact 
locality is where the words ‘‘ Round Wolds” occur half a mile east 
of Swadlincote, near bottom left-hand corner of Quarter-sheet 
No. 71 8.W. (Nottingham) of the One-inch Ordnance Survey. It is 
referred to on page 203 of Mr. H. B. Woodward’s new work on 
“The Geology of England and Wales.” It exhibits, in my opinion, 
1. Four distinct systems or periods of strata, viz. Carboniferous, 
Permian, Trias, and Drift. Of the lowermost group of these rocks 
we have about 40 feet of Coal-measures, consisting of two thin coal- 
seams; four or five beds of fire-clay, three of which measure about 
26 feet in the aggregate, and immediately below the Permians 
are variegated coal-shales with numerous nodules, and one or 
two bands of a variety of red hematite, and an occasional large 
concretionary mass of altered siliceo-ferruginous sandstone with 
cone-in-cone structure. 
The Permian strata appear to consist of dark red compact marl, 
some thin bands of tea-green marl, and a bed of semiconsolidated 
breccia, containing a variety of crystalline, slaty, igneous, and other 
rock-fragments.? 
Upon these lie yellowish soft sandstones, flaggy beds, marls, 
1 See GrotocicaL Macazrne, No. 1, p. 17, January, 1887. 
2 See GeoLocicat Magazine, Vol, for 18865, p. 333. 
