360 Geological Society. 



are charged with sliells similar to those of the highest members of the 

 basin of Vienna. Some of the beds pass into concretionary masses 

 of an oolitic limestone similar to that which is described at other places 

 in the next section. 



II. Section from Radkersburg on the south to Riegersberg on the 

 north, exhibiting the structure of the youngest zone of the tertiary 

 deposits of Styria, and its relations to certain volcanic rocks. 



Several lofty and serrated ridges of volcanic rocks range from Hain- 

 feldt on the Raab towards Radkersburg, and a section made along 

 their western face offers the following phaenomena. 



At Straden shelly sands and pebble beds are capped by irregularly 

 columnar basaltic lava with olivine, &c. 



The hill of Poppendorf exhibits in great detail the structure of this 

 younger tertiary zone. Marls, sands, and conglomerates, occupy its 

 lower and middle parts, together with many beds of calcareous shelly 

 grits, indurated marlstone, limestone, &c. the whole being very mi- 

 caceous, and the organic remains identical with those of Radkersburg. 

 These are overlaid by micaceo-calcareous sand containing concre- 

 tionary masses of a perfect oolite which is quarried as a building stone, 

 and which differs from the great oolite of Bath only by its concretionary 

 structure and tlie tertiary shells associated with it. 



The fine-grained oolite passes upwards into other concretionary 

 beds something like English cornbrash, and the whole is surmounted 

 by micaceous sands and marls. In an adjoining hill near Gnaess, 

 these beds inclosing shells, alternate with volcanic peperino made 

 up of basaltic lava, scoria, vitreous felspar, olivine, pyroxene, the 

 detritus of tertiary rocks and shells, &c. ; and on the summit the 

 peperino in a more compact state is quarried as a building stone. 

 The conical hills of Gleichenberg, overlying the shelly sands, are 

 entirely of volcanic origin, and were probably the centre of igneous 

 eruption in these parts. Here the predominating rock is a coarse 

 trachyte used for millstones (felspathic porphyry, probably analogous 

 to the Porphyre molaire of Beudant), and with it are associated ba- 

 saltic lavas, scoria, and fine peperino, which near Hainfeldt repose 

 upon the sands. Considerably to the north of the Raab the volcanic 

 conglomerate on which the castle stands, is also recumbent upon the 

 shelly sands and pebble beds. 



From these and several other examples in the neighbourhood, the 

 authors infer, that no tests can be established by wiiich the relative 

 ages of these various igneous rocks can be fixed, since the same ter- 

 tiary strata are in one place covered by basaltic lava, in a second by 

 trachyte, in a third by volcanic conglomerate, whilst in a fourth they 

 alternate with peperino. 



In conclusion they remark : 



That the lowest tertiary strata near Eibeswald must from tlieir 

 high inclination have been considerably elevated after their de- 

 position. 



That the various groups described, unquestionably represent, — 

 1st, the Faleotherian and Calcaire grossier period :— 2ndly, The crag 



and 



