20 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 28, 



SO as not to be visible; therefore it is not known whether the two 

 lower members of the new red sandstone or the higher coal-measures 

 crop out in that space. In the turn of the river Medloek, red and 

 variegated clays, parted by thin bands of gritstone, make their ap- 

 pearance. These are succeeded by similar deposits, containing the 

 limestones and thin coals of Ardwick, and afterwards all the coal- 

 measures of Bradford and Clayton, comprising the whole of the 

 known part of the upper and the higher part of the middle division 

 of the coal-field. The dip is nearly south-west, at angles varying 

 from 18° to 25°. The coal-measures at Bank Bridge have been 

 thrown down by a fault to an unknown depth, and are covered by 

 upper new red sandstone for a distance of about three miles. The 

 last-named formation crops out near Jericho Clough, and the coal- 

 measures of the middle field are afterwards seen in the river-course 

 at Waterhouses dipping westwards, at an angle of about 60°. The 

 strata of Ardwick are the highest members of the coal-field that I 

 have met with ; but whether they constitute the termination of the 

 field, and none other are to be met with on their dip, yet remains to 

 be proved. 



(5.) Collyhurst Section, 



This section is one mile ^ 



north of Manchester, and ^J> 



shows the three lower mem- 

 bers of the new red sandstone 

 formation, successively out- 

 cropping and graduating into 

 each other. The shell marls 

 and lower new red sandstone 

 are in great force, and the last-named rock rests unconformably on 

 the coal-measures of the middle field. 



This section has been fully described by me, and the description is 

 published in the volume of the Transactions of the British Associa- 

 tion for 184-4, and in the first volume of the Transactions of the 

 Manchester Geological Society. But there is one circumstance not 

 fully described in either of those papers. It is, that at the turn in 

 the river Irk, where the lower new red sandstone can be seen gra- 

 dually passing into red clays containing numerous circular impres- 

 sions, and immediately above the clays, there occurs a bed of con- 

 glomerate sandstone of a brownish colour, with sharp angular grains 

 and pebbles sometimes reaching to the bulk of a common marble. 

 This conglomerate presents more of the usual characters of the lower 

 new red sandstone than the thick rock of Collyhurst, the grains of 

 which are all well-rounded, and never, I believe, attain the size of a 

 small pea. In my section it is classed with the magnesian limestone, 

 but I now consider that it ought to be grouped with the lower new 

 red sandstone. Immediately above this conglomerate are red and 

 variegated clays, amongst which are nodules of a fine-grained red- 

 dish stone containing a considerable amount of iron and lime. 



N.N.E. Middle coal. S.S.W 



