386 
ELEMENTS OE GEOLOGY. 
Sir R. Murchison, from Perm, a Russian province, where it 
occupies an area twice the size of France, and contains a 
great abundance and variety of fossils, both vertebrate and 
invertebrate. Professor Sedgwick in 1832* described what 
is now recognized as the central member of this group, the 
Magnesian limestone, showing that it attained a thickness 
of 600 feet along the north-east of England, in the counties 
of Durham, Yorkshire, and Nottinghamshire, its lower part 
often passing into a fossiliferous marl-slate and resting on an 
inferior Red Sandstone, the equivalent of the Rothliegendes 
of Germany. It has since been shown that some of the Red 
Sandstones of newer date also belong to the Permian group; 
and it appears from the observations of Mr. Binney, Sir R. 
Murchison, Mr. Harkness, and others, that it is in the region 
where the limestone is most largely developed, as, for exam¬ 
ple, in the county of Durham, that the associated red sand¬ 
stones or sedimentary rocks are thinnest, whereas in the 
country where the latter are thickest the calcareous mem¬ 
ber is reduced to thirty, or even sometimes to ten feet. It 
is clear, therefore, says Mr. Hull, that the sedimentary region 
in the north of England area has been to the westward, and 
the calcareous area to the eastward; and that in this group 
there has been a development from opposite directions of 
the two types of strata. 
In illustration of this he has given us the following table: 
THICKNESS OF PERMIAN STRATA IN NORTH OF ENGLAND. 
N.W. of England. N.E. of England. 
Feet. 
600 
10-30 
3000 
Feet. 
50-100 
600 
l00-250t 
Upper Permian (^Sedimentary) . 
Middle “ (Calcareous) 
Lower “ (Sedimentary) . 
Upper Permian. —What is called in this table the Upper 
Permian will be seen to attain its chief thickness in the 
north-w^est, or on the coast of Cumberland, as at St. Bee’s 
Head, where it is described by Sir Roderick Murchison as 
consisting of massive red sandstones with gypsum resting 
on a thin course of Magnesian Limestone with fossils, which 
again is connected with the Lower Red Sandstone, resem¬ 
bling the upper one in such a manner that the whole forms 
a continuous series. No fossil foot-prints have been found 
in this Upper as in the Lower Red Sandstone. 
* Trans. Geol. Soc. Lend., Second Series, vol. iii., p. 37.., 
t Edward Hull, Ternary Classification, Quart. Journ. of Science, No. xxiii., 
1869. 
