596 



J. E. MAER ON THE PREDEYONIAN 



green shales. In addition, this band and the last (Dd4) are 

 described as containing the "■ Colonies." 



III. Silurian Bocks. 



The Silurian epoch includes M. Barrande's etages E-H. Unlike 

 the Cambrians, the prevailing rocks of this series are limestones, 

 although shales occur here and there, and preponderate at the base 

 of the series. From the manner in which the limestones vary in 

 thickness, and thin out altogether in horizontal areas of no great 

 extent, and from the way in which they differ from one another in 

 lithological character, we should expect them to possess peculiar 

 faunas ; and this is found to be the case. 



Etage E is divided into two bands by M. Barrande, the upper 

 one calcareous, the lower one chiefly argillaceous. 



E e 1 is found with invariable characters at all parts of the 

 basin where exposed. It is composed chiefly of shales, but becomes 

 calcareous towards the top, passing into E e 2. It rests, as stated 

 by M. Barrande (Def. des Col. iv. p. 109), unconformably upon 

 the beds of D ; such unconformity is well seen on the W. side of 

 the Slivenec valley, about 300 yards W.N.W. of Gross Kuchel (see 

 fig. 3). Here the lowest bed of E e 1 consists of a calcareous 

 conglomerate with greenish pebbles, about four inches in thickness, 

 resting on the denuded edges of greenish shales, underlain by thick 

 yellow grits. 



Fig. 3. — Section on the N. side of Slivenec Valley. 

 (Length about 15 yards.) 



E. 



1. Olive-green shales. "j 



2. Grits. I T) /i fi 



3. Olive-green shales, 2 feet thick at | "^ ^ ^• 



W. end, 5 feet thick at E. end. J 



Conglomeratic bed ^ 

 6-9 inches. I -j-, ^ 



"Wafer" grapto- f "^ ® ^• 

 litic shales. I 



Unfortunately, in most localities, the junction between D and E 

 is concealed, or, where exposed, is a faulted one ; in the neigh- 

 bourhood of Beroun, however, it seems to be well exposed in two 

 vaUeys, viz. near Kraluv Dvur and near Chodaun. 



In each locality the grits of Dd5 are succeeded by similar 

 grits with unstratified black bands, which I would refer to the 

 base of E, and considered to have been derived by denudation from 



