$g| M.deHoff's Geological 



contains trochites, spiral univalves (terebrae), and a few un- 

 fletermined bivalves ; but there are no traces of corals ob- 

 servable in it. 



. Argillaceous transition slate forms a considerable mass of 

 rock in the eastern part of the Thuringerwald, from Stein- 

 heide to Lehesten, where it constitutes the whole of the 

 northern, and a great part of the southern side ; it is in ge- 

 neral black or grey, easily divides into thin and even plates, 

 and is worked as roofing slate in numerous places, near 

 Sonnenberg, Lehesten, &c. It contains beds of drawing 

 slate, whetstone slate, and flinty slate. Nodules of pyrites 

 and quartz are also found in it. A singular variety of slate 

 occurs at Feldherg, near Sonnenberg ; it divides into very 

 slender separate pieces, possessing a certain degree of tena- 

 cious softness, which renders them fit to be employed as 

 styles, or pencils for writing on slate. It is pretended that 

 this variety is not found elsewhere. 



Greywacke occurs solely on the east of the Thuringerwald, 

 where it occasionally appears to alternate with slate. 

 M. Heim regards it as situated beneath it. With few ex- 

 ceptions it occurs only on the south, or Franconian side, and 

 especially in the valleys running towards the Kronach ; its 

 beds are sometimes as much as twelve feet thick; but they 

 become thinner as they approach the slate, and then form 

 greywacke slate. The greywacke is most frequently grey, 

 sometimes whitish, blackish, reddish, yellow, or greenish. 

 Its paste is the same as that of the argillaceous slates : it 

 contains felspar, quartz, silvery mica, and a reddish rock 

 analogous to porphyry ; the whole in rounded grains, that 

 are rarely of the size of a nut. Rocks ^re observable near 

 Oberhasloch, in which the greywacke resembles a conr 

 glomerate. 



These conglomerates, and micaceous or quartzose red sand-? 

 stones (konglomerat rothes und graues liegende), which 

 together compose the formation named red sandstone, con- 

 sidered the most ancient of the secondary formations, are 

 the most extensively spread of all the rocks in the Thurin- 

 gerwald. It is this rock that forms the commencement of 



