HOPKINS ON THE LAKE DISTRICT. 4 83 
of irregularities due to dislocation, if it now existed over the whole of 
the district. 
13. A very general conclusion in the Theory of Elevation which I 
have elsewhere developed, is this :—that the directions of dislocation 
will approximately coincide with those of the mean dip, or with those 
of the mean strike of the beds. Accidental deviations from this law 
may of course arise from local and irregular causes which can in no way 
be reduced to calculation ; but all such deviations are not to be deemed 
anomalous. They may not unfrequently proceed from causes which, 
though in a certain degree local, may be brought within the sphere 
of our mechanical theory, and may even in some instances afford one 
of the best tests of its accuracy. The above rule, however, will in most 
cases be approximately true, and may be applied with great facility. 
The dislocations of the older rocks in the district with which we 
are occupied must be considered with reference to both the great 
movements, or series of movements, of which we here recognize the 
effects, viz. the movements prior to the deposition of the Carbonife- 
rous series, and those by which it was subsequently dislocated, since 
the older rocks must necessarily have been acted on by both these 
movements. The great longitudinal dislocations which accompanied 
the first of these movements would, according to our theory, approxi- 
mately coincide with the mean strike of the older beds, so far at 
least as that strike coincides with that originally given to those beds 
by the first general action of the elevatory force to which the com- 
mencement, and therefore the directions of the dislocations, are to be 
referred. A subsequent movement, following a different law, might 
destroy this coincidence of direction. Thus, supposing the original 
movement of the older beds to have given thema strike to the N.N.E. 
and §.8.W.; and conceive the dome-like configuration of the district 
to have been given by a subsequent and local movement ; then would 
the coincidence of direction in the longitudinal Fig. 12. 
dislocations and the strike be destroyed. Thus, O23 
let A B represent a line of fracture, and a 6, pa- 
rallel to it, a line of strike, the direction of the 
dip bemg denoted by the arrow at a; then will 
a 6 be a horizontal line on the stratum passing 
through a 6. Conceive now a subsequent and 
local movement to produce a dome-like elevation, 
of which O should be the highest point ; the line 
a6 will no longer remain horizontal, 7. e. it will 
no longer be the line of strike, which will evidently 
assume some such position as a 0’, running round 
the last-formed elevation. The degree of devia- 
tion of a 0’ from a 4 will depend on the pre-exist- “ 
ing inclination of the older beds, and on the strike 
and inclination which the local movement alone 
over the whole district is real or imaginary; this is the elevation with which 
we are properly concerned in any theory on the subject. The mere superficial 
elevation (or that of the actual surface independently of local irregularities) is only 
here important so far as it gives us an approximation to the ere elevation. 
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