Reviews — The Work of the Geological Survey. 4:77 



pre-Triassic system, which traverses the Vale of Glamorgan. A long 

 series of north-north-west faults, the course of which across the 

 pre-Triassic folds has been worked out in detail, belongs to the 

 system which is certainly in part of post-Triassic, but probably 

 in part also of pre-Triassic age. Lastly, a series of parallel dis- 

 turbances of great magnitude, which traverse the northern part of 

 the coalfield, the Old Red Sandstone and the Lower Palaaozoio 

 rocks, and which have determined the river drainage, may be 

 assigned to the system of which the Neath disturbance is a well- 

 known example. This third system, which is characterized by 

 folding and overthrusting on a large scale, runs in a general west- 

 south-west direction, and from its remarkable influence on the 

 surface configuration is believed to be of later date than the others. 



In the Midland district the work has been confined to the southern 

 and western part of the Derbyshire and Nottinghamshire Coalfield. 

 Mr. Wedd has mapped out the various beds of Millstone Grit which 

 were not separated in the original survey, and one result of his 

 work has been to relegate a considerable tract of country which was 

 formerly regarded as Goal-measures to the Millstone Grit formation. 

 Mr. Gibson has continued his researches on the higher measures of 

 this coalfield, and has obtained additional evidence to prove that 

 beds above the Top Hard, which have been brought to light in the 

 Gelding shafts and in the Thurgarton boring, are palgeontologically, 

 lithologically, and stratigraphically comparable with the higher 

 measures occurring in other Midland coalfields. As he points out, 

 there seems no escape from the conclusion that the Pennine elevation, 

 with the consequent breaking up of the syncline, was subsequent to 

 their deposition. He has also obtained evidence of the existence of 

 marine conditions during the deposition of the Coal-measures at 

 several horizons, both low down and high up in the series, and in 

 view of these facts he naturally asks whether a much larger proportion 

 of our Coal-measures has not been formed under marine conditions 

 than is generally supposed. In working out the palasontology of 

 the coal Mr. Gibson has received valuable aid from Dr. Wheelton 

 Hind, whose name frequently recurs in this Summary of Progress. 



In Scotland the I'evision of the Carboniferous areas has been 

 commenced in the eastern part of the Midland Valley. Mr. Wilson 

 has re-examined the oil-shale field to the west of Edinburgh, and 

 calls attention in his report to the fact that the shales in that 

 region, with few exceptions, deteriorate both in the quantity and 

 quality of the oil as they are followed downwards. If this should 

 prove to be a general law, it will obviously have a very important 

 bearing on estimates of the value of any area in which the oil-shale 

 horizons exist, and raise an interesting problem as to the nature of 

 the processes by which the oil-producing compounds have been 

 concentrated near the existing surface. 



The examination of the coast between Dunbar and Cockburns- 

 path has enabled Mr. Clough to prepare a detailed section of the 

 Carboniferous Limestone series, and to show that the beds which 

 dip under the sea along a portion of the coast are probably very near 



