Geological Survey of the Yorkshire: Coast. 289 
capable of filling it; and if we could suppose that all the higher 
members of the series once extended over the space through 
which the dyke runs, which of these strata could supply the re- 
quisite materials ? Why are the numerous cracks and fissures, in 
the oolite and other strata, not filled with the same substance ? 
And, since so many of the upper beds consist of limestone, why 
does the dyke contain so small a portion of calcareous matter ? 
If the fissure was filled from above, by secretions from beds that 
have been washed away, why does it not every where reach the 
surface? Or rather, as it is harder than the strata washed away 
from it, why does it not every where stand up above the surface 
like a wall, as it does at Langbargh and some other places? Be- 
sides, why are its contents disposed in large oblong blocks, lying 
across the fissure; and not rather arranged in a stratified forin, 
or suspended in stalactitic masses? Above all,’ why is the dyke 
throughout its whole length composed of crystallized matter, and 
that matter not at all affected by the nature of the various strata 
through which it passes? In its progress from Maybecks to 
Cockfield, it crosses the blue limestone and the sandstone strata 
above it, the coal measures of our hills, the aluminous strata, 
the red sandstone of Cleveland, the magnesian limestone, and 
the Durham coal measures, arriving at, or approaching, the 
metalliferous limestone; yet the diversified nature of the beds 
through which it runs has no effect on it. Now, as the substance 
and structure of the dyke are nearly uniform, and have no con- 
nection with the nature or composition of the beds which it tra- 
verses, we are compelled to think, that it is all derived from one 
common source, and that source not above but below. And 
when we also see along its course, effects produced by it, exactly 
corresponding with the effects of ignited matter, what are we to 
believe, but that its substance has been forced upwards ina state 
of igneous fusion ?—Hence, as we have seen that this dyke is 
connected with slips or breaks of the strata, it is natural to con- 
clude, that the same kind of agency which forced up ignited 
matter into fissures of the strata, may have been employed in 
raising the strata themselves, out of the ocean in which they were 
formed,” 
This work is embellished with a geological map, a section of 
the strata, and seventeen lithographic plates, coloured. Those 
who are fond of a fine plate, would probably have preferred that 
they should have been engraved on copper; but these, which are 
executed by one of the artists, give an excellent idea of the va- 
rious subjects they are meant to illustrate, aud perhaps more na- 
tural than finer engravings. 
Pp2 An 
