E. MINERALOGY AND GEOLOGY. 2OI 



NATURE OF LOESS. 



In an inaugural address by Jentzsch, discussing the "qua- 

 ternary strata in the vicinity of Dresden, and the formation 

 of loess in general," he concludes, from careful examination 

 of and experiments with loess, that all its essential character- 

 istics are simply consequences of the degree of comminution, 

 and are sufficient to separate it geologically from loam and 

 clay. Its particles are chiefly from about 0.0008 to 0.0016 of 

 an inch in diameter, and those of plastic clay and loam about 

 0.00024 to 0.0004 of an inch. The cohesion of the loess is con- 

 sequently less than that of clay, and it falls to pieces in wa- 

 ter on this account, as well as because the angle of friction is 

 lessened by water. Absence of stratification is explained as 

 resulting from the obliteration of sharply defined margins of 

 the earlier deposits by this efiect of water; and strata are 

 consequently only recognizable when the layers are in difier- 

 ent states of comminution. The properties, as well as the 

 location and contents, indicate that it is a fluviatile deposit 

 in overflowed portions of valleys. 19 C^ January 25,1873, 

 130. 



VOLCANIC ERUPTIONS IN ICELAND. 



The past winter was very mild in the southern portion of 

 Iceland, but quite severe in the northern. In the middle of 

 January an eruption of the volcanoes in the great Yokul 

 Mountains, in the southeast corner of the island, took place, 

 which continued with unusual violence for about a week, and 

 then suddenly ceased. Since then no fire has been noticed. 

 Large quantities of ashes have fallen on different localities, 

 but it is believed that the deep bed of snow protected the 

 pasture lands from destruction. Volcanic eruptions took 

 place at the same time in Chili. 1 (7, 1873, 128. 



THE TOURMALINE. 



A work has just been published on the tourmaline by Dr. 

 Hamlin, of Maine, so well known as a specialist on the subject 

 of gems, and as having one of the finest private collections in 

 the United States. He makes special reference to the beau- 

 tiful and matchless crystals found in the State of Maine, and 

 gives four very fine illustrations in color by Prang. He also 



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