AUSTEN — EXTENSION OF THE COAL-MEASURES. 46* 



Explanation of the Map, Plate I. 



The map which accompanies the present communication must not 

 be viewed as a geological one — as representing the actual arrange- 

 ment of the mineral masses which compose the present surface — nor 

 yet as a map of Western Europe at any definite period of past time. 



One of the objects of the memoir which it illustrates is to trace 

 out the gradual formation of an old terrestrial area, that over which 

 the coal-growths ultimately established themselves. It is hoped that 

 the descriptive portions of the paper will be found nearly sufficient 

 for this purpose, and that the introduction of a few leading lines, 

 such as may serve to indicate the direction of the masses which in 

 turn imparted a definite physical configuration to the area in question, 

 is all that is requisite to guide the reader, and enable him to follow 

 more easily the kind of evidence on which the conclusions have been 

 based. 



Over the British portion of the area, a local group, known as the 

 " Old Red Sandstone," has been tinted, because it serves to indicate 

 very definite physical conditions at a definite period. From the date 

 of this group the Carboniferous formation may be viewed as a great 

 fluvio- marine series of the later Palaeozoic period, during the whole 

 of which the fades of the contemporary marine fauna was such as is 

 known as that of the Mountain-limestone series. It must however 

 be borne in mind, that in the North of Ireland the distinction be- 

 tween the marine Carboniferous sandstones and lacustrine Old Red 

 Sandstone has not been traced as it has for the South. 



A very extensive series of maps would be required to convey any 

 adequate representation of the successive changes which Western 

 Europe underwent in its physical arrangement ere it reached the 

 maximum extent of terrestrial surface which it presented at the time 

 of the great coal-growths ; but the time may come when general 

 views as to past conditions will require to be thus illustrated. 



The geographical arrangements on which the internal basin con- 

 taining the Palaeozoic fluvio-marine groups depended were preserved 

 through a long subsequent period ; the same area became that of the 

 " New Red conglomerates, sands, and clays" of English geologists, 

 and which, if in part " Permian" and part " Triassic," are such only 

 in the form of equivalents, these groups being here the accumulations 

 and depositions of lacustrine waters and their tributary rivers. 



No restoration of the area of the coal-growths has been attempted 

 on the side of the old Scandinavian chain ; it could have easily 

 been shown, however, that all the subsequent secondary and tertiary 

 formations had their limits against this mass, and that all these lines 

 have been carrried downwards by the progressive subsidence to which 

 this chain has been subjected, even to times very near to the present. 

 In the Coal-measure period the materials of the sandstones of our 

 northern and midland districts must have been brought down by 

 streams which had their origins in that region. 



We have only to imagine an extension of the Scandinavian chain, 

 encroaching on the area of the North Sea, and along a line north and 



