THE PERMIAN SYSTHM W> 



The fauna is restricted (about 140 species) and peculiarly 

 distributed; fossils are most abundant in the Middle limestones, 

 which seem to have formed a shell bank, and only a few Lamelli- 

 branchs and Gastropods survive into the Upper Beds. Fish 

 remains occur at two horizons the Marl Slate and the flexible 

 limestones, and in the beds just above these deposits. Productus 

 horridus is characteristic of the Lower and Middle limestones. 

 For other common fossils see Fig. 105. 



In Yorkshire, near Pontefract and elsewhere, the limestones are 

 thinner, but the marl slates are thicker than in Durham, and 

 sometimes rest on white and yellow sands, which in turn rest on 

 an eroded surface of red marls and sandstones belonging to the 

 Upper Coal-measures (see p. 298). In South Yorkshire the 

 succession may be summarised as follows : 



Feet. 

 Upper red marls ... 50 



Upper (Brotherton) limestone 



Middle red marls 



Middle limestone, thick-bedded 



Lower limestone 



Blue limestones and shales 



Quicksands and breccia 



50 to 120 

 30 to 50 

 150 to 200 

 about 120 

 5 to 15 

 10 to 20 



From 430 to 570 



Traced southward into Nottinghamshire, the Upper limestone 

 thins southward and is at the same time overlapped by the Trias, 

 so that the thickness of the Permian at its outcrop is very much 

 diminished, being as follows : 



Feet. 



Middle marls and sandstones . . . . 20 to 30 

 Magnesian limestone (lower) . . . . . 60 to 70 

 Marl slates 30 to 50 



Southward near Kimberley the limestone passes into a yellow 

 calcareous sandstone about 30 feet thick, resting on 15 to 20 

 feet of shaly marl, with a few feet of coarse breccia at the base. 

 This change and diminution in thickness is evidently an indication 

 that we are in this direction approaching the southern shore of the 

 Permian Sea. The breccia contains angular fragments of sandstone 

 and shale derived from the Coal-measures on which it rests, 

 together with pebbles of slate, quartz, and quartzite, and it is not 

 unlikely that these were derived from a northerly prolongation or 

 the Charnwood rocka, 



From borings made in search of coal near Haxey in Lincoln- 

 shire, and near Newark on the eastern border of Notts, it is known 

 that the Permian limestones and marls exist in full force below 

 these places. At Haxey the Permian was entered at 1183 from 



