144 GEOGNOSY AND GEOLOGY. 
into it, when their mutual stratification is conformable. The clay slate is 
here quite characteristic, and presents itself in the most varied modifications, 
among which chlorite and talcose occur in particular places. Next to this 
comes grauwacke, as grauwacke shale, along which are arranged sandstone 
and quartz rock. Compact limestone and dolomite occur here only in 
proportion to the floetz. Fossil remains are found only in single beds, and 
coal is seldom concentrated in large masses. The principal species are : 
Clay Slate, as common roof, alum, and calcareous clay slate. Its 
stratification is very perfect ; sometimes entirely straight, sometimes bent in 
greater or less curves, and again contorted in every imaginable manner, it 
occasionally traverses whole mountains. It is almost always found in consi- 
derable masses, and frequently alternates with the other members of the 
transition shale, as with chlorite schist, talc slate, grauwacke and grauwacke 
slate, hornslate, jasper, silicious shale, and quartz rock. In places where no 
abnormal masses could operate on it, it occurs as slate clay. 
Chlorite and Tale Slate, of a character much as in the bottom series. 
They are nearly allied to schalstein, into which they pass, as also into 
chlorite and talc flagstone. 
Grauwacke, in all its modifications, as the common, fine, small, coarse, 
and large grain, as slaty, and as grauwacke slate. Sometimes one modifi- 
cation prevails, sometimes another. Thecolors vary much ; grey, however, 
appears to predominate. Oxyde of iron, penetrating the stone in an ochrey 
form, gives to it a red coloring. A soil is produced by its decomposition 
which acts more advantageously on vegetation than clay slate. 
Silictous Conglomerate. This passes into grauwacke, and is similarly 
constituted. It is generally colored red by oxyde of iron. 
Sandstone, which passes into quartz rock, and when mixed with mica 
approaches more or less to mica schist. Its decomposition consists in a 
mechanical division. It is generally clay or quartz sandstone, and of a 
light color. 
Quartz rock. This not seldom passes into the above-mentioned sand- 
stone. Its colors are white, brown, red, and violet; it imbeds certain 
rock species of this formation, as silicious shale, clay slate, and some others. 
It resists weathering very well, on which account it exerts great influence 
on the form of mountains. 
Limestone. This is most generally compact, pure or mixed with silex. 
of grey or variegated colors, the latter often connected with the pre- 
sence of corals. Marble sometimes occurs independently, and sometimes 
connected with compact limestone, into which it passes. It runs into 
calcareous clay slate and marble flagstone. | Nodules of limestone often lie 
in clay slate, and are frequently ranged in such succession as to form beds 
by their contact, which, when of great extent and size, form prominent 
components of mountain masses. Where it alternates with strata of the 
transition slate, it exhibits a distinct stratification, which is sometimes greatly 
modified by the presence of mica. Caves abound in it, these being 
generally lined and ornamented with stalactital and stalagmital matter. 
Examples are seen in the Baumanns-cave and Biels-cave in the Hartz, the 
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