360 Mr. H. E. Strickland on the Elevator y Forces 



having been elevated as a solid ; for the downcast side being 

 lower by several thousand feet than the upcast, the syenite, if 

 fluid, could not have been raised to its present position, but 

 would have overflowed the downcast side to a great distance. 



Admitting this wall-like mass of syenite to have been forced 

 up from below in a solid state, we at once obtain a clue to the 

 vertical or highly inclined (sometimes reversed) position of the 

 sedimentary strata on the west, or upcast side of the Malvern 

 fidge.' " "^ ''•^ ^ * ' ''* '^^- < •' 



' 'It'ap^afirt, thefi/ iiliat the Malvern district, though forming 

 part of a great line of fault, yet exhibits the phsenomena of a 

 fault under a very complicated aspect. To explain this I must 

 refer for a moment to a few elementary principles. 



In the simplest form of a fault, when one portion of a hori- 

 zontal stratum is elevated by an equally diff'used pressure from 

 below, while the other portion remains at rest, the stratum pre- 

 serves its horizontality up to the very plane of separation ; or, 

 more frequently, the friction of the two masses causes the strata 

 to bend slightly towards each other on the opposite surfaces of 

 the fault. Again, if the upward pressure be confined to a line 

 instead of being spread over a surface, the strata are thrown in 

 opposite directions, and an anticlinal is the result. 



But the Malvern region presents us with a combination of 

 both these kinds of forces, and of both their resulting phsenomena. 

 There has been an elevatory force diff'used more or less equally 

 under a vast area, which has heaved up in a mass the entire 

 region for hundreds of miles to the westward of the Malvern 

 axis. And there has also been a local force applied immediately 

 beneath this axis, which has given an extra amount of elevation 

 to the marginal portion of the upcast area. 



It is this excessive development of motive force at the very 

 margin of an elevated region, and in immediate contact with a 

 non-elevated tract, that renders the phsenomena of the Malvern 

 Hills peculiarly anomalous. Under ordinary circumstances, when 

 an upward force is applied locally along a line, it acts equally on 

 both sides of that line, elevating the strata, as already shown, 

 into an anticlinal position. If, however, the resistance be greater 

 on one side of the axis than the other, a certain amount of dis- 

 placement ensues, and the anticlinal an'angement is combined 

 with that of a fault. The Malvern elevation is probably an ex- 

 treme and unusually exaggerated instance of the last class of 

 phaenomena. If we could strip off the thick mantle of New Red 

 Sandstone which conceals the eastern side of this axis, we should 

 probably find the strata from the Caradoc sandstone up to the 

 Coal-measures more or less upturned at their edges. (See Plate I.) 

 So vast a force as was required to elevate the syenitic axis could 



