STRATIGRAPHICAL GEOLOGY. 435 



part older than the greywacke beds. In the year 1836, 

 Murchison and Sedgwick proved that the shales belong to 

 the Carboniferous formation and repose upon the true 

 greywacke series with interbedded conglomerates, shales, and 

 fossiliferous limestone. The whole complex of strata is so 

 strongly compressed and folded, and the rocks show such 

 striking metamorphic features, that Murchison and Sedgwick 

 both were of opinion they must be of Cambrian age. But 

 Lonsdale, to whom the fossils were entrusted for examination 

 in 1837, expressed his conviction that the Killas greywacke 

 complex must be younger than the Silurian system and older 

 than the Carboniferous system. Although at first a little 

 incredulous, after a careful revision of their sections, the two 

 geologists accepted Lonsdale's conclusion, and together wrote 

 a large memoir (1839) on the newly-identified system of strata, 

 which they termed the "Devonian," between the upper 

 Silurian and lower Carboniferous. In addition to the grey- 

 wacke series in Devon and Cornwall, they assigned to the 

 Devonian system the Old Red Sandstone in Scotland, whose 

 distribution, thickness, divisions, and fossils had been the 

 subject of their earlier memoir published in 1828. 



Many doubts were cast upon the independence of this new 

 system, and Murchison and Sedgwick resolved to test their 

 results by means of comparative researches in the Continental 

 districts where the Wernerian " Transitional Series " had been 

 chiefly studied. The two friends travelled in the summer 

 of 1839 through the Rhine district, Westphalia, the Harz, 

 Nassau, Thuringia, the Fichtel mountains ; in the companion- 

 ship of De Verneuil, they also travelled in Belgium and the 

 neighbourhood of Boulogne. In 1842, Murchison and Sedg- 

 wick published a memoir in which they tried to show that a 

 great portion of the shales and limestones, as well as the 

 sandstones, greywackes, and conglomerates exposed in the 

 Rhineland belonged to the Devonian and Silurian system, 

 and that in the Fichtel mountains Devonian deposits were 

 present, but no Silurian. These results were partially 

 erroneous with regard to the Silurian division, since the 

 whole of the lower greywacke series in the Rhine district 

 was said to be Silurian, and the Silurian deposits in the 

 Fichtel mountains were entirely overlooked. Still, the in- 

 vestigations of the two British geologists proved incontestably 

 that there lay between the Carboniferous system and the 



