TRANSLATIONS AND NOTICES 
GEOLOGICAL MEMOIRS. 
On the Structure of the Schwarzwald. Extracted from a Letter to 
Proressor Leonuarp. By M. Fromuerz. 
[From Leonhard and Bronn’s Jahrbuch, 1847, p. 813.] 
THE transition formations have a considerable extent in the southern 
Schwarzwald. They donot form, as was at one time supposed, three 
separate, altogether isolated deposits, but a connected, though highly 
dislocated range, passing across the mountains from Badenweiler to 
Lenzkirch, only interrupted by granite between the valleys of the 
Menzenschwand and the Aha. In this tract the transition rocks 
consist of clay-slate, mostly metamorphic ; of greywacke-slate, formed 
by the fine attrition of the materials of which the transition conglo- 
merates were formed; and lastly of these conglomerates or the so- 
called greywackes. Beds of anthracite have been observed in several 
places in the transition formation of the southern Schwarzwald, but 
have never been found worth working. Limestone is entirely want- 
ing. 
mahether these beds are Silurian or Devonian cannot, from the 
total absence of a fauna, be determined ; but that they are transition, 
the remains of plants in the anthracite beds, together with the mine- 
ralogical character of the rocks and the occurrence of anthracite, 
leave no doubt. The following facts, from which some important 
deductions relative to the mode of formation of the Schwarzwald 
may be drawn, seem deserving of notice. 
1. The rolled fragments in the Schwarzwald greywacke prove that 
before the deposition of the transition strata plutonic masses existed 
there, and that consequently a portion of the Schwarzwald belongs 
to the most ancient geological periods. Among the pebbles of the 
greywacke of the southern Schwarzwald there occur granites of very 
many varieties; coarse or fine granular, porphyritic, with white or 
red felspar, with mica of various colours, &c. The greater number 
of these granites are still found in the present Schwarzwald moun- 
VOL, IV.—PART II. D 
