Calcareous 
Chain of the 
North. 
140 Professor Sepawick on the 
it has often been triumphantly appealed to, as affording a proof 
that such formations, may, at least in some instances, be of aqueous 
origin. With this view, I ascended High Teesdale in the autumn 
of 1821, and, although interrupted by torrents of rain which 
rendered the banks of the river in many places inaccessible, 
succeeded in examining some localities which promised to throw 
light on the true relations of the trap. Last summer I again 
passed through that ®alley, and had an opportunity of verifying 
the observations of the preceding year. My time was, however, 
too limited to enable me to complete the task which I had un- 
dertaken, What is now offered to the Society, must, therefore, 
be considered as an imperfect sketch drawn from observations, 
directed, almost entirely, to the elucidation of the true relations 
of the trap to the contiguous strata. Under such circumstances 
it will be important carefully to separate such appearances as 
are doubtful or hypothetical from those which are plainly 
exhibited; and to draw our conclusions, respecting the origin 
of the basaltic rocks, from those facts only which are established 
on the clearest evidence*. 
Those who are acquainted with the geological features of 
England, must have remarked the chain of calcareous hills 
which runs nearly north and south through a part of Yorkshire, 
Durham, and Northumberland. The rocks forming all the higher 
parts of this chain are composed of limestone, sandstone, and 
shale (slate-clay) repeated in numerous alternations. From their 
continuity and prevailing characters, they are undoubtedly mem- 
bers of one formation—the mountain or metalliferous limestone. 
Yet, in districts considerably remote from each other, it is only 
* Since the Paper was first read to the Society, the author has made a third visit 
to High Teesdale, and as all his previous observations have been carefully revised, he 
has considerable confidence in the general accuracy of the details which are now 
offered to the public. 
