338 Reviews and Notices of Books. 



the north and south of the Lippe ; hut, taken by itself, it is quite 

 sufficient to indicate a group corresponding with the great mass 

 of our middle and upper chalk, and which is ranged, together with 

 the overlying arenaceous division, under the Senonien group of 

 M. d'Orbigny. The two together form a tract which is isolated 

 from the rest of the cretaceous series by the alluvial and turf 

 formations of the valleys of the Ems and the Lippe, so that their 

 immediate superposition on the next group is nowhere to be seen. 

 B. 1. The Planer, whose age and position at one time was such 

 a matter of doubt and difficulty to some English geologists, is, 

 according to M. Roemer, the most constant in its organic remains 

 and mineral ogical character of all the cretaceous rocks of New 

 Germany. He estimates its thickness at more than 800 feet ; of 

 this, the upper portion is mostly a compact, pure, calcareous rock, 

 the lower a marly calcareous clay. At Bochum, an intercalated 

 band of greensand is seen, and in the range of the Planer, east- 

 ward, such bands increase, and serve to subdivide the formation 

 into two natural groups. In this form it can be traced round 

 the whole of the bay or amphitheatre, from Muhlheim, near the 

 Hhein, to Lichtenau, and thence to Bevergern, near the Ems, and 

 along this whole line it is only separated from the older forma- 

 tions by the intervention of the sands of Essen. 



The list of fossil species from this great group is very limited ; 

 such as there are occur abundantly. Inoceramus mytoloides (1. 

 is most common ; next in frequency is Terebratula pisum ; also 

 Tereb. striatula ; T. semiglobosa (1. ch.) ; T. gracilis ; T. splicata 

 (m. ch.) ; Spondylus spinosus (u. ch.) ; andHolaster subglobosus ; 

 Ammonites peramplus (1. ch.) ; Nautilus elegans. A suite which 

 refers the Planer to the lower chalk. 



B. 2. The Flammen mergel is a name first given to some beds 

 which are seen between Goslar and Seesen, and which occur also in 

 Westphalia. The strata consist of argillaceous limestone, more 

 or less siliceous, of a light gray, with dark streaks. From its 

 hardness, this group usually shows as a projecting edge between 

 the ridges of the Hils sandstone and the Planer, and is as much 

 as 100 feet thick. It is best seen from Dbrenschlucht to Biele- 

 feld. Its geological position, in the Teutoberger Wold, is next, 

 beneath the Planer. The only fossil quoted by Mr lloemer is 

 Avicula gryphnp.oides (u. gr. s.) 



B. 3. Greensand of Essen. — Under the head of the •' green - 

 sand of Essen," Mr Roemer groups a very variable series of ac- 

 cumulations, consisting sometimes of very coarse conglomerates 

 or sandstones, and of fine calcareous marls. They vary much in 

 thickness ; their position is constant, being in immediate juxta- 

 position on the highly inclined beds of the carboniferous groups, 

 and overlaid by the beds of the Planer, with which the marly beds 

 agree mineralogically. 



