Correspondence. 233 
graphics, I have ventured to give very briefly the information 
required. 
The so-called burning well has ceased to exist for nearly a cen- 
tury. It was fed byaspring; and petroleum and naphtha also found 
their way from rents in the rock into the well with the water, and 
were occasionally ignited. Springs of petroleum, on a much larger 
scale than the Broseley one, are met with in the neighbourhood, and 
the yield of each of these was formerly much greater than at pre- 
sent. Many hogsheads from one of these were exported some years 
ago, under the name of ‘Betton’s British Oil. The rocks were 
tapped by driving a level through one of the sandstone rocks of the 
Coal-measures; but these are now drained, and very little is found 
to flow from them. This is also the case with*a spring in Tar-Batch 
Dingle, about a mile and a half lower down the Severn: the tar- 
spring is still to be seen, but the quantity given out is smaller, we 
apprehend, than when it first gave its name to the Dingle. 
With regard to its origin, it is well known that many of the trees 
of the Carboniferous period were resinous, like our pines; and it is 
easy to suppose that the oil pressed out from the accumulated masses 
of vegetable matter which formed the coal-seams would become 
absorbed by the sand-beds above them, and that this oil would 
naturally find its way out when tapped by shafts, or levels, or water- 
courses. Joun Ranvatt, F.G.S. 
Mavetry, Satop: April 24, 1865. 
ARE THE SEA-ROCKS OF CHARNWOOD FOREST LAURENTIAN ? 
To the Editor of the GroLocicaL MAGAZINE. 
Srr,—In the last number of the GrotogicaL MaGazine, Sir R. 
Murchison, in his paper ‘On the Laurentian Rocks of Great Britain, 
Bavaria, and Bohemia,’ brings prominently into notice the strike of 
the beds of the old rocks of the North-west Highlands (fundamental 
gneiss) as being a feature distinguishing them from the Cambrian 
and other aqueous rocks of our Island. Jt may be useful to notice 
that the old slate-rocks of Charnwood Forest have precisely this 
same strike, viz. S.E. by N.W. ‘These rocks, covering an irregular 
square of about ten miles, have been (doubtfully, I think) classed as 
‘Cambrian.’ They have many features that distinguish them from 
the ‘typical Cambrians’ of the ‘ Longmynd ;’ among these may be 
noticed the great variety of rocks,—four species of so-called igneous 
rock (Granite, Syenite, Greenstone, and Basalt * )—almost every 
variety of slate, from coarse-grained grauwacké to fine roofing- 
slate,—the remarkable metamorphic character of the whole group: 
slate passing by insensible gradations into greenstone, and the 
occurrence of gneiss, in almost close contact with granite; there 
* T have part of a fine hexagon from the anticlinal line: it is a coarse-grained 
basalt. 
