HUGHES: ADAM SEDGWICK. 
261 
formations between the coal-measures and the lias), notwithstanding- 
their violent mechanical origin, have several characters in common, 
which enables us to connect them together, and, for general purposes 
of comparison, to regard them as one group." He points out the 
palaeontological distinction between the Upper Limestones of the 
group (Muschelkalk) and the Lower (the Magnesian Limestone). 
While attaching due weight to such a great unconformity for 
purposes of local classification he cautious us against pushing this 
kind of evidence too far. " We have no right," he says, " to assume, 
nor is there any reason to believe, that such disturbing forces either 
acted uniformly or simultaneously throughout the world. Formations 
which in one country are unconformable, may in another be parallel 
to each other, and so intimately connected as to appear the produc- 
tion of one epoch." 
He gives the following classification in descending order : — 
Upper Red Marl and Gypsum. 
Upper Red Sandstone. 
Grey thin-bedded Limestone. 
Lower Red Marl and Gypsum. 
Yellow Magnesian Limestone. 
Marls and thin beds of Magnesian Limestone. 
Lower Red Sandstone. 
Some difficulty occurs in following the various accounts of the • 
lowest beds of the group, but it can, I think, be easily explained. The 
Lower Magnesian Limestone passes down into red or yellow sandy 
beds at Pontefract. So in the Eden Valley the " brockram " or base- 
ment conglomerate of the Poikilitic series rests on red and yellow sand- 
stones. But these are of totally different age. In the sandy beds 
of the roadside cliff near the great quarries just outside Pontefract, 
I have myself found Schizodus obscurus. These beds undoubtedly 
belong to the Magnesian Limestone Series. 
In the Eden Valley, on the other hand, it was found by boring 
near Appleby that the red colour did not extend lower than a little 
over 100ft. into the rock. It was obviously a stain produced by 
infiltration from above. And there is in the Woodwardian Museum 
a collection of fossil plants from the N.W. margin of the same area 
from red beds formerly referred to the Poikilitic series which contain 
nothing but Upper Carboniferous species. 
