112 DR. A. H. COX : REPORT ON MAGNETIC DISTURBANCES IN NORTHAMPTONSHIRE 
Valley follows for several miles, between Hoby and Melton, a course which is 
coincident with the probable prolongation of the fault-line. Now the lines of the 
Eempstone and Sileby Faults would intersect at a point in the Wreak Valley just 
south-east of Asfordby Village, and about two miles west of Melton Mowbray. It 
is precisely at this assumed intersection-point of the two faults that the main 
magnetic disturbing centre is situated, as indicated by the intersection of the arrows 
showing the “ relative ” horizontal disturbing forces at Melton and Asfordby respec¬ 
tively (see p. 82). 
That all four lines should intersect at one and the same point cannot be an 
accidental coincidence, especially when account is taken of the fact that the Lough¬ 
borough and Rempstone disturbing forces also intersect on the fault-line.* It affords 
a strong presumption that the magnetic disturbances may originate in connexion 
with the fault, and that magnetic material is concentrated at particular localities 
along the fault-line. 
So far then we have a fault-line running east-south-east between Rempstone and 
Melton Mowbray with disturbing centres near these two localities, resulting in large 
disturbances being measured at the stations Rempstone, Loughborough, Asfordby, 
Melton, and presumably accounting for the large disturbance at Waltham. The 
remaining stations at which large disturbances were observed, namely. Pen Hill and 
Nottingham, are also situated on other fault-lines. 
A fault of small throw has been proved at Owthorpe to cut the Mesozoic Rocks, t 
This fault strikes 30° N. of West to 30° S. of East, that is, nearly parallel to the 
Rempstone Fault, the downthrow being again to the north-east.- The fault if 
continued for three miles in the same direction would pass almost underneath the 
observation-station at Pen Hill. Five miles farther on along the same line, at White 
Lodge, a number of small step-faults are seen, all throwing to the north-east. 
The “Nottingham” observation-station is situated half a mile east-north-east of 
Bramcote Church, and is on one of the most pronounced zones of faulting in the 
whole district. Faults pass on either side of the station at distances which cannot 
exceed a quarter of a mile,J while a third fault passes three-quarters of a mile to the 
south. These three faults are all parallel to one another, and they take an east-west 
course which defines the southern end of the exposed portion of the Nottinghamshire 
coalfield. 
* The intersection-point at Rempstone, and possibly also the one at Asfordby, does not appear as 
mathematically exact so far as the plan, or map, is concerned. This is readily accounted for by the action 
of one or more of several factors, among the more obvious being that the fault-plane is presumably inclined 
to the vertical, and therefore, with increase in depth, its projection on to a horizontal plane suffers a 
lateral displacement. Further, the north pole of the disturbing mass need not necessarily be situate 
exactly on the line of the fault-plane. The latter factor invalidates any calculations as to depth of origin 
of the disturbances which might otherwise be made from the lateral displacement of the fault-projection. 
t ‘ Geol. Survey Map,’ 1-inch (New Series), Sheet 142. 
i ‘Geol. Survey Map,’ 1-inch (New Series), Sheet 126. 
