TRANSACTIONS OF THE SECTIONS. 
589 
II. The second order of lines of elevation which Mr. Cony- 
beare considers, includes all those which appear to have affected 
our strata between the tertiary epoch and that of the magnesian 
lime,—a wide range. But the materials which the phenomena 
of our island here present are so little marked as to forbid 
more than a vague generality, although M. de Beaumont enu¬ 
merates four distinct epochs of disturbance during this period. 
Here Mr. Conybeare specifies, 1. the unconformable elevation 
of the Yorkshire oolites beneath the cretaceous Wolds, E.and W.; 
2. the want of conformity of the cretaceous and oolitic series 
on the confines of Dorset and Devon ; 3. the dislocation of the 
alum shale of Yorkshire in the prolongation of the great Cleve¬ 
land trap dyke which intersects the magnesian limestone and 
oolites, and ranges E. and W.; 4. the 90-fathom dyke of the 
Newcastle coal-field, which throws down the magnesian lime, 
ranges E. and W. 10 miles, where it joins the Stubbick fault, 
extending in the same direction transversely across nearly the 
whole breadth of the great Penine chain. The trap dykes 
which intersect this coal-field in a parallel direction may pro¬ 
bably be referred to the same epoch—which we see to have 
been posterior to the magnesian limestone—but are without 
evidence as to the minimum point of its geological antiquity ; 
5. the oolites of Northern Scotland (Brora) are elevated at 
their contact with the granitic chains, and generally in lines 
parallel to those chains. For the reasons above stated, these 
cases will hardly admit of any comparison with the views of 
M. de Beaumont. 
III. The third period of disturbance and elevation noticed 
coincides with the Systeme des Pays Bas of M. de Beaumont, 
being posterior to the completion of the carboniferous series, 
and anterior to that of magnesian limestone, which rests in 
comparatively horizontal planes on the often highly inclined 
strata of the former. The geological chronology is here there¬ 
fore determined within very narrow limits, as these two forma¬ 
tions are generally the immediately successive terms in the 
geological series. Yet even here a short interval appears to 
have been interposed, marked by the deposition of the Ponte¬ 
fract sandstone (the equivalent of the rothe todte) in the North 
of England; and this interval appears to have included two 
periods of disturbance, for the Pontefract rock is, according to 
Mr. Sedgwick, often unconformable both to the inferior coal 
measures and superior magnesian limestone. 
The English disturbances of this period however do not 
appear to have proceeded in any system of parallel lines. 
Those in the North of England generally range N. and S., and 
