Fault As the Westeru Boundary of the Moira Coalfield. It Is Thus
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GEOLOGY OF LEICESTERSHIRE. Church to Willesley Hall. The town of Ashby is itself situated upon them, and just outside it, on the E., a fault runs, like most of the great dislocations, from N.N.W. to S.S.E. From this line the stratification dips eastward to Coleorton, and westward to Moira ; hence it coincides with the Anticlinal Axis of the coalfield. We possess evidence to show that the strata under discussion are at least 1000 feet in thickness; and that scarcely any seam of coal contained in them exceeds 2t feet. A coal not quite so thick was worked many years ago at Pistern Hill, north of Smisby, another (or possibly the same) at Smisby itself. A similar seam is seen in a brickyard between Smisby and Ashby; and coals of about the same thickness are found in the Railway Cutting near Breach Hill Farm, in a well at Ashby Union Workhouse, and elsewhere. There seems to be a gradual dip of the stratification of these lower Coal Measures towards the S., and in consequence some higher beds set in in that direction. We have already mentioned (at page 90) that a seam of some thickness was worked about the year 1830 at Alton Grange; but having never been able to obtain any reliable particulars, we are unable to identify it with any seam in the regular series. D. The Western Division; m· Moira and Swadlincote Coalfield. It has been already mentioned that barren coal measures extend :from the Coleorton Fault to a great line of dislocation running from Woodville to Willesley. This we call the Boothorpe Fault, from a hamlet where its effects are visible on the surface. A few of the lowest workable seams extend in places for a short distance to the eastward of this line ; but, on the whole, it cuts off the profitable )foira Basin on the W. from the barren lower coal measures of Ash by on its E. The Boothorpe Fault does not appear to be one sharp fracture, but a succession of steps, with high tilting of the stratifica tion spread over a width of 200 or 300 yards. The result is a dislocation of the beds to the amount of about 1100 feet in the neighbourhood of Boothorpe and Woodville. About a mile to the W. of this, and on the whole parallel to it, runs another fault, known as the Great ]foira, or l.Ianunatt's Fault. This is a clear line of nearly vertical fracture, throwing down the strata to the E., or up to theW., to an extent varying up to 120 yards in the neighbourhood of Moira. From this line for about a mile to the W. the beds rise slightly to the W, ; till the known and worked portion of the field appears to be bounded by another great fault running like the others from N.N.W. to S.S.E. At Donisthorpe, where this fault was proved some 60 years ago, it received the name of the Thomtree Fault; but so little is known of it to the northward that the Government Surveyors have not ventured to lay it down on the Ordnance Map. It probably runs from Oakthorpe, by the W. end of Donisthorpe Church, along the edge of the Red Formation, a little W. of Barrat Pool, to Castle Gresley Station, and thence nearly along the highroad to Stanton and Stapenbi11. We must for the present consider this fault as the westeru boundary of the Moira Coalfield. It is thus .