224 Professor Sedgwick and Mr. Murchison on the 



base-line ; and we hoped to find on some part of it clear evidence of the true 

 succession of the inferior groups. We approached this line, in the first instance, 

 by a traverse from the neighbourhood of Frankfort ; and by a long series of other 

 traverses through Nassau and the adjacent tracts of country, we endeavoured to 

 connect together the great formations which are spread out between Westphalia 

 and the chain of the Taunus. 



We afterwards crossed the plains of Hessia to the chain of the Hartz, portions 

 of which we examined in some detail ; and anxious (before our return to the pro- 

 vinces on the Rhine) to see a country which has become classical through the la- 

 bours of Count Miinster, we made one long traverse from the borders of the Thii- 

 ringerwald to the north flank of the Fichtelgebirge. 



The results arrived at from the preceding observations may be briefly stated as 

 follows : — 



1. From the great similarity of mineral structure as well as of fossils, from the common lines of 

 strike and dislocation, and from many other common accidents of position, we concluded tliat the old 

 rocks of all the above-mentioned regions belonged to one connected series of deposits — that they all 

 gave unequivocal exhibitions of a Devonian system — and that none of the subordinate groups were of 

 very great antiquity. 



2. That the great series of rocks expanded between Westphalia and the Taunus might be subdivided 

 into the following groups in a descending order : — 



(1.) A true carboniferous series, partly based on mountain limestone in its ordinary form, and partly 

 on alum slate, flinty slate, and thin-bedded black limestone. 



(9.) A series of shales, slates and limestones (afterwards found to include the great limestone of West- 

 phalia), containing many fossils identical with those of South Devon. 



(3.) A very large ill-defined group, with several characteristic Silurian fossils mixed with other organic 

 forms unknown in England. 



(4.) Masses of slate of an older mineral type, and with few traces of fossils ; placed by us, provisionally, 

 in the lowest part of the Silurian or the highest part of the Cambrian system. 



We wish to state distinctly that we came to these conclusions before we examined 

 any of the provinces on the left bank of the Rhine, and that (with the exception 

 of some adjustments among our lines of demarcation) we still continue to adhere to 

 them. We may also add, that though we found no fossils in the chain of the 

 Taunus to assist us in determining its relative age ; yet were we led to conclude, 

 by the consistent evidences of our sections, that it did not belong to the lowest of 

 the preceding groups. But after crossing to the left bank of the Rhine we found 

 fossil evidence sufficient to prove, that the chain of the Hundsriick (and conse- 

 quently that the chain of the Taunus, which is a physical prolongation of the 

 Hundsriick) was merely a portion of the great group above mentioned (No. 3.) in a 

 highly altered and mineralized form. Our examination of the provinces on the 

 left bank of the Rhine only commenced in the latter part of the summer, when we 

 began with a series of traverses from the ilundsriick, through the basin of the 



