The deposits of the useful minerals & rocks; their origin, form, and content . and south, to the Brohl river and to the Sieg respectively;few occurrences are known in the Devonian slate north of this the north the district is bounded by the Dierscheid and Lennef rivers. The Lower and Middle Devonian slate, consisting of grauwacke andsubordinate clay-slate, rests upon the Gedinnian, with which it formsanticlines and synclines, these in places being steeply inclined. As Zelenyhas shown, a relation undoubtedly exists between the tectonics of thedistrict and the occurrence of lodes, th
The deposits of the useful minerals & rocks; their origin, form, and content . and south, to the Brohl river and to the Sieg respectively;few occurrences are known in the Devonian slate north of this the north the district is bounded by the Dierscheid and Lennef rivers. The Lower and Middle Devonian slate, consisting of grauwacke andsubordinate clay-slate, rests upon the Gedinnian, with which it formsanticlines and synclines, these in places being steeply inclined. As Zelenyhas shown, a relation undoubtedly exists between the tectonics of thedistrict and the occurrence of lodes, these latter occurring along faultsand subsidences, a similar relation in the case of Siegerland having beendemonstrated by Denckmauu. This geological position may be particu-larly well observed in the occurrences at and in the neighbourhood ofLiiderich. While the strike of the lodes varies greatly, the dip, which is generallybetween 60°-70° and but rarely as low as 45°, is always steeper than that ofthe country-rock, though in the same direction. In relation to width and. Hcmscnei^ Beds Lodes I n/hiU Faults Qvarllife Actual Assumed Fig. 338.—Map showing lodes iu the Berg district. Zeleuy. Geol. Landesaiist. 1912. THE LEAD-SILVEK-ZINC LODES 695 nature the lodes exhibit great differences. The narrow lodes show distinctwalls, some of these being clean fissures and others clay-partings. Thefilling consists of decomposed clay-slate and fragments of grauwackeand arkose, traversed by quartz veins and ore. With large lodes thisbrecciated structure is less pronounced. In these, large blocks of country-rock, which though wrenched from the parent mass, much folded,broken, contorted, and traversed by fractures, have usually maintainedtheir internal coherence, constitute the principal mass, which consequentlyoften presents a banded appearance. With lodes so filled a distinctseparation from the country-rock no longer exists, and often only throughthe unmistakable occurrence of a lithomar
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
