98 nil. PERMIAN FORMATION. 



outcrop (the only portion, of a doubtless extensive Permian area, that 

 is open to our inspection) occupy a long, narrow, and fairly rectilinear 

 band of country whioh ranges X.N.W. and S.S.E. from the coasts of 

 Durham on the north to the town of Nottingham on the south, and 

 Beparate the triassic rocks on the one (east) haul from the car- 

 boniferous rocks on the other (west.) From Nottingham to Watlas, 

 Bedale, in the north-riding of Yorkshire, this hand of Permian roeks, 

 though very fluctuating in width and rarely more than five miles 

 across, is unbroken, though in the northern part of its range the mag- 

 nesian limestone occupies a very narrow tract of country. Between 

 Bedale and the valley of the Tees west of Darlington, triassic rocks over- 

 lap the Permian deposits, and rest on millstone grit and Yoredale rocks, 

 the magnesiau limestone only showing at the surface in certain outliers 

 hetween Bedale and Richmond. Northwards from the Tees the mag- 

 nesian limestone ranges through Durham, broadening out so as to 

 occupy most of the eastern portion of that county from Hartlepool and 

 ! hi the south, to South Shields and Tynemouth on the 



north. The western boundary of the magnesiau limestone is well 

 defined and usually forms an abrupt and often lofty escarpment, over- 

 looking the low undulating lauds of the Coalfields of Yorkshire and 

 Durham, and the bolder contour of the millstone grit country inter- 

 vening. 



The summit of the escarpment being reached, we find an extended 

 plain gradually declining towards the east, and in a general way the 

 slope of the ground will be determined by the dip of the beds. The 

 eastern boundary of the magnesian limestone is not well defined. In 

 many places it is covered by thick deposits of drift, and its junction 

 with the overlying triassic rocks is rarely visible ; when seen, however, 

 (as, for instance, in the Cinderhill and Bestwood quarries, near 

 Nottingham) a certain want of conformity is apparent between the 

 two series, and this unconformability is also inferred from the southerly 

 and westerly overlaps of Permian by triassic rocks, (a.) 



Looking at the present distribution of the Permian rocks of the 

 north-east of England, a fact that strikes us at once is the pronounced 

 onoonformability between the Permian and the Carboniferous 

 rocks. In its range from Nottingham to Tynemouth the magnesian 

 limestone overlaps two coalfields — the Yorkshire and the Durham; 

 for a considerable part of the distance, it is true, the trend of the 

 magnesian limestone escarpment runs parallel with the north and 

 south strike of the measures of these coalfields, but when we reach 

 the confines of these basins, in particular the northern limits of the 

 greai Sorkshire coalfield and the southern extremity of the Durham, 

 the true unoonformability of the Permian and carboniferous systems 



• be noted, nowe i 1 notion of the amount of 



unconformity between the two formations may be thus obtai l. The overlap 



takes plaoe in the directions in which the Permii i as I shall presently 



shew, naturally attenuate, thui I ce of certain of the Permian members 



mi th.' south mi. i west i- due less to their subsequent denudation Hum to their 

 oi iginaJ attenuation. 



