AND LEIOESTEESHIRE AND THEIR RELATIONS TO GEOLOGICAL STRUCTURE. 111 
2. The Coincidences between the Fault-Lines and the Magnetic Disturbances. 
The association of “ magnetic-ridge lines ”—that is lines or zones of considerable 
magnetic disturbance—with faults, has been noted by Rucker and Thorpe* in the 
cases of the Great Glen Fault, the Southern Boundary Fault of the Highlands, and 
the Lilleshall—Church Stretton Fault. 
In the district now being considered an examination of the distribution of the 
disturbing forces establishes a clear connexion between the magnetic disturbances 
and a system of east-west to south-east—north-west faulting. It can be shown that 
all the observation stations at which large magnetic disturbances, whether horizontal 
or vertical, were recorded, are situated on or in the immediate proximity to known 
fault-lines or their probable prolongations. In most cases these faults have only been 
proved in the Mesozoic rocks, but some of them are seen to affect both Mesozoic and 
Palaeozoic formations. 
Mr. Walker has deduced (p. 82) “ the presence of a pronounced line of disturbing 
matter running nearly east- and west from Melton Mowbray to between Rempstone 
and Loughborough. Along this line the vertical disturbing forces attain their 
maxima at two points, one just south of Rempstone, the other a little west of 
Melton Mowbray.”—G.W.W. 
Near Rempstone a line of faulting has been definitely proved by the Officers of the 
Geological Survey.! Within one mile to the south of this village a pair of faults 
displaces the outcrops of the Mesozoic rocks—Keuper Marl, Rhmtic, and Lower Lias— 
that of the Rhsetic Beds being shifted as much as one and a-half miles. The faults 
are trough-faults throwing towards one another, the downthrow of the southern and 
larger fault being to the north, but the extent of the throw is not known. The 
strike of the faults is 20° S. of East to 20° N. of West, and they have been followed 
over a distance of five miles, so that they pass between Rempstone and Lough¬ 
borough. (See map, Plate Ap. 3.) It is highly significant that the faulting crosses 
the intersection point of the arrows indicative of the direction of “ relative ” horizontal 
disturbance at Rempstone and Loughborough respectively. 
East of Rempstone the line of faulting cannot be followed on the ground itself 
owing to the covering of Boulder Clay and to the absence of features among the soft 
Lower Lias Clays. But if prolonged, the line would pass near to Melton Mowbray. 
In the Wreak Valley another fault—The Sileby Faulty—has been proved to take 
an east-north-east course for over four miles. This fault, like the one at Rempstone, 
cuts Keuper Marl, Rhaetic, and Lower Lias, and it also has a downthrow to the north. 
At the village of Hoby, six miles west of Melton Mowbray, it runs under the alluvium 
of the Wreak Valley, and cannot, therefore, be followed farther eastward ; but, 
presumably, it continues under the alluvium, for it is noticeable that the Wreak 
* ‘ Phil. Trans.,’ Ser. A, vol. 188 (1896), p. 656, and Plate 14. 
t ‘ Geol. Survey Map,’ 1-inch (New Series), Sheet 142. 
1 “The Geology of the Country near Leicester,” ‘ Mem. Geol. Survey,’ 1903, p. 68. 
