proceedings: geological society 31 



At the 287th meeting, November 25, 1914, informal communications 

 were presented by W. T. Schaller on: 



1. So-called vanadic ocher. 



2. The minerals of northern New Jersey which are now represented by 

 casts. 



Regular program: 



Edgar T. Wherry: A peculiar oolite from Bethlehem, Pa. The 

 grains in an oohte limestone show a division, parallel to the bedding, 

 into a light and a dark portion, the latter being the lower. Chemical 

 analysis showed the grains to be higher in dolomite, quartz, kaolin, 

 limonite, and carbon, and lower in calcite and siderite, than the matrix. 

 Microscopic study shows the nuclei to be imbedded in the dark material, 

 which is heaped up around them. It is concluded that the original 

 grains consisted of concentric layers of aragonite, containing more or 

 less carbon, and that, after solidification of the sediment, circulating 

 waters dissolved away the former, the carbon and the nuclei falling to 

 the bottom of the cavities. These were later filled up again by secondary 

 dolomite, the coarse crystallization of which is evident in the sections. 

 The carbon precipitated pyrite from iron sulphate-bearing waters, and, 

 finally, this was changed to limonite by weathering. 



J. S. Diller: The recent eruptions of Lassen Peak. Although erup- 

 tions have occurred at Mt. Baker and St. Helens as late as 1842 and 

 1843 the great volcanoes of the Cascade Range are generally regarded as 

 extinct. Lassen Peak, the southern terminus of the Cascade Range, 

 has long been noted for its fumaroles and solfataras, but until recently 

 there has been no explosive action. On May 30, 1914, a series of explosive 

 eruptions began, and up to the middle of November of the same year 

 more than 60 eruptions had occurred. 



Some of the various forms of ejected dust-laden vapors, rise more 

 than 10,000 feet above the mountain summit, and the progress of the 

 development of the new crater, from its starting point within the old 

 crater of Lassen Peak up to the western side, where it has broken through 

 the old rim, was illustrated by lantern slides. 



Fine dust was scattered over the country in various directions for 

 nearly a dozen miles, and close to the crater the large rock fragments 

 ejected form a stratified rim 25 feet or more in thickness about the new 

 crater. So far as known none of the material was molten at the time of 

 its ejection. The ejected vapors which were almost wholly steam, were 

 sHghtly acid, with sulphurous odors. W. C. Wheeler treated the 

 ejected dust with water and found both sulphur and chlorine in the 

 resulting acid solution, showing that the ejected vapors were similar to 

 those of the solfataras in the region. 



There was once vigorous solfataric action in the old crater, but it had 

 entirely ceased. Its rejuvenation and extension is a matter of special 

 interest. Flashes of light and fljdng luminous fragments have been 

 reported on good authority, and as the crater gets larger and deeper 

 hotter material is ejected. 



