228 Professor Sedgwick and Mr. Murchison on the 



cording to our own classification, is chiefly intended to indicate approximately 

 the relations of the great subdivisions of the older sedimentary deposits. 

 Those persons who wish to study the varied composition of the rocks of igneous 

 origin with which this region abounds, must consult the original works of the 

 distinguished field-geologists of the Prussian school to whom we have referred. 



PART I. — Older Formations on the right bank of the Rhine. 

 Carboniferous Rocks of Westphalia, {a, h, and c of the Sections.) 



(See Map, Plate XXIV. No. 6, 6^ and 6*, and Sections 2 and 4, Plate XXIII.) 



Our earliest perception of the order and succession of the older strata in the 

 Rhenish provinces was acquired by an examination of the rocks upon the right 

 bank of the Rhine. We shall therefore first give a very brief account of that part 

 of the region which contains a productive coal-field, and is based upon the carbo- 

 niferous or mountain limestone ; and we shall next describe, at greater length, the 

 various strata which successively rise out from beneath it, and are thrown up into 

 the broken and convulsed region which extends into Nassau. 



Coal Measures. — This field, so rich in coal and iron, and containing the staple 

 of the manufacturing wealth of Prussia, is surmounted on its northern boundary 

 by the green sand and cretaceous rocks of Lower Westphalia, and to the west or 

 towards the Rhine, by tertiary rocks and superficial detritus. That part of it 

 which is productive is expressed by the dark colour of the Map (No. 6). It is of 

 a triangular form, having its vertex near to the town of Unna ; while its base (which 

 lies towards the Rhine) ranges from the neighbourhood of Elberfeldt, and passes 

 through Kettwig and Werden to the country beyond Miilheim. 



We do not profess to describe the structure of this coal-field in any detail, a task which has been already 

 in a great measure accomplished by German geologists*. It is sufficient for our purpose to observe, that 

 in lithological characters, in its fossils, and in its beds of sandstone and shale with their courses of coal 

 and ironstone, it is not to be distinguished from many coal-fields of our own country. In its range from 

 W.S.W. to E.N.E. it has been aff"ected by many powerful convulsions, the most remarkable of which 

 appear in the form of anticlinal lines parallel to the strike; and divide, on a ground plan, the area into 

 triangular masses, the apices of which terminate to the E.N.E. These elevations have raised up the lower 

 beds of sandstone and shale (6', of Map), which are unproductive of coal, and have thrown the overlying 

 or productive measures into a number of troughs. The lower strata consist in part of grits (not unhke 



♦ See the Map and papers of Von Oeynhausen and Von Dechen — Nbggerath's Westphalia (Das Ge- 

 birge in Rheinland-Westphalen, vol. ii.). 



