WILLIAM SMITH : HIS MAPS AND MEMOIRS 
177 
of experience by the side of him, is at a loss how to proceed. What, 
therefore, has he to do but to seek out all the analogous cases, and, even 
if not strictly analogous, to learn, if he can, by the known the way to the 
unknown. 
" Now there are certain partial interruptions to the regular courses 
of the coal-beds in the great northern run of the coal-measures which 
extends through Derbyshire and Yorkshire, which may help to elucidate 
the mysteries at the two extremities of that long coal district, and to 
satisfy us whether they really are terminations, or only great and 
unusual deflections in the ranges of those strata, deeply hidden and 
unexplored, and which, better known (perhaps only by experiment), 
may enable us to judge of the probability of uniting or extending our 
coal-fields. 
For solving these important questions on our coal-fields, some few 
years since noticed by Mr. Coneybeare in a very general way (not 
altogether correct), I think much may be deduced, both from the 
observations of the geological phenomena, and from experience. 
" Some are not certainly extricable in the direction of their ranges, 
while others appear to be so ; and, therefore, there is a probability of 
some of them being united. 
" Some of the coal-fields, particularly in the middle of the island, 
seem not yet wrought to any well defined limits of the coal series ; and, 
consequently, in such cases there is good ground for expecting an 
extension ; and especially as geology, by its settled order of superposition 
in the rocks, does away old erroneous notions of cut-ofis, &c., by the red 
rock, and by the interposition of faults or dikes. 
"From the numerous instances of now well-ascertained undulations 
across the general ranges of the strata, by which their planes are formed 
into coverns, and intermediately, in the reverse of these forms, so that 
the strata of coal may rise on one side up to an unconformable covering, 
cut ofi by the red marl or red rock, there may be good reason to expect 
the coal-measures to go down again on the other side of the so-called 
anticlinal line at no great distance ; and especially where it can be 
ascertained that such lateral rise of strata has not brought up the 
deepest part of the coal series ; but, where the mill-stone grit or moun- 
tain limestone appears, there, with certain exceptions, the case may be 
decisive. 
