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Observations (m Serpentine and Dialhge Rocks. By Dr A. 

 Boue'. In a Letter to Professor Jameson. Communicated 

 by the Author. 



I HE geological relations of serpentine are still but imperfectly 

 known ; for it is not many years since we were assured of the 

 existence of transition serpentines in the form of short beds, or 

 large masses in the veins, or bed-like veins, of the greenstone 

 (diabase) of the Pyrenees (St Pe, and Valley of Baretons) ; in the 

 grey wacke of Girvan and Ballantrae in Scotland (Jameson), and 

 of Bastberg in the Hartz ; in the transition slates of the northern 

 Fichtelgebirge, and of the Vosges ; in the transition limestone 

 of Willendorf in Austria ; in the Carpatho-Appenine sandstone 

 of Waidhofen in Lower Austria, of Monte Ferrato, near Prato, 

 Impruneta,Creboli, &c. in Tuscany, and of Borghetta in Liguria. 

 Veins of serpentine have been detected by the geologists of Scot- 

 land, in the old red sandstone of Forfarshire. 



Some of these masses present characters illustrative of an ig- 

 neous and violent origin, and throw light on the true situation 

 and formation of other serpentines, whose contact with neigh- 

 bouring rocks either has been but imperfectly seen, or not seen 

 at all. The serpentine of Willendorf is a fine example of the 

 injection of this rock amongst older strata. It is situated about 

 half a mile to the west of that village, and on the right hand 

 side of the road leading to Granbach. The limestone hills are 

 bordered by reddish precipices, in the midst of which, the geo- 

 gnost sees with astonishment a thick columnar mass of serpentine 

 rising through the limestone, to the height of 100 feet, and 

 fairly terminating in the surrounding limestone rock. This 

 mass is 60 feet broad below, 40 feet broad at top, has an undu- 

 lating contour, and a blackish knotted surface, as if composed of 

 irregular spherical bodies. Small veins of asbestus and calca^ 

 reous spar are contained in it, but no distinct diallage rock. It 

 is intimately united with the transition magnesian limestone 

 which it intersects ; and between the two rocks there is a breccia 

 composed of a mixture of the limestone and serpentine. Even 

 the limestone itself is impregnated with serpentine matter. All 

 the neighbouring rocks are more or less vesicular, and deeply 



