206 PETROLOGY. 



Green, W. L. On a Probable Origin for many Magncsian Limestones 

 and Dolomites, for the Serpentine Streaks in Yerdc Antique 

 Marble, and for the Serpentine found in Eozoon Canadense and 

 other Limestone Eossils. Journ. It. Geol. Soc. Ireland, ser. 2, 

 vol. iv. pt. 3, pp. 140-143. 

 The lava of the Hawaiian group of islands is a basic variety eon- 

 taining much olivine ; and when it is broken up by the sea a large 

 quantity of olivine-sand is formed. A mixture of this with coral- 

 sand is common over the group, extending 400 miles. The olivine- 

 sand also penetrates into the pores of the coral-reef rock. Such 

 mixtures might give rise by metamorphism to serpentines, verde 

 antiques, and dolomites ; and ancient rocks of these classes may have 

 been so formed. The olivine-sand might penetrate organic matter, 

 and so lead to mineralization, such as in Eozo'dn. Suggests that the red 

 clays and manganiferous muds of the Pacific are a residue from lavas 

 and volcanic dust. E. T. H. 



Gtimbel, Dr. C. W. Yariolit von Berneck im Pichtelgebirge. [Vario- 

 lite from Berneck in the Pichtelgebirge.] N. Jahrh. Heft i. 

 pp. 42, 43. 



Asserts the relation of this rock to diabase, against the views of 

 Zirkel. 



Guyerdet, A. Analyse et Examen du Depot laisse par les dernieres 

 Inondations de la Garonne an Eaubourg Saint-Cyprien a Toulouse. 

 [Analysis of Elood-mud of the Garonne at Toulouse.] Comjpt. 

 Bend. Assoc. Frang. pp. 577-581. 



5 other analyses of river-mud are quoted for comparison. 



Hardman, E. T. On the Origin of Anthracite : with Suggestions as 

 to the possible Correlation in Time and Manner of Production of 

 the Aiithracites of Southern Ireland, Wales, Devonshire, and 

 Erance. Journ. li. Geol. Soc. Ireland, ser. 2, vol. iv. pt. 3, 

 pp. 200-209. 

 There are two theories of the origin of anthracite — that it is due to 

 crumpling of strata, and that it is caused by plutonic influences. The 

 author maintains the latter. After glancing at the chemistry of the 

 process by which woody matter may gradually change into anthracite 

 or even graphite, it is pointed out that this will not accoinit for the 

 partial alteration of beds of coal in the same coal-field, and subject to 

 the same conditions. Such alteration cannot be ascribed to flexuring ; 

 for contorted anthracitic coal-fields are rare, whilst many bituminous 

 coal-districts are highly disturbed. In most coal-districts there is 

 evidence of an outburst of igneous rock of later date than the coal, 

 sufiiciently near, either to visibly effect the alteration, or of such extent 

 that hidden masses may have approached close enough to the Coal 

 Measures to have driven off the volatile matter. All the immediate coal- 

 fields N.E. of a line through the semibituminous coal of Leitrim and 



