PETROLOGICAL ABSTRACTS AND REVIEWS 
ALBERT JOHANNSEN 
SOsMAN, R. B., and Merwin, H. E. “Data on the Intrusion 
Temperature of the Palisade Diabase,” Jour. Wash. Acad. 
Sct., III (1913), 389-95. 
Slabs of the underlying Newark shale and arkosic sandstone have 
in many cases been “floated” up into the igneous rock of the Palisade 
diabase of New York and New Jersey, apparently while the latter was 
still liquid. This paper deals with studies made of the comparative 
fusion points of the diabase and the arkose. The former begins to melt 
at 1,150. but does not flow till 1,225°, while most of the latter is fused at 
1,150. The inclusions in the Palisade diabase, however, show no trace 
of fusion, and the authors conclude that the fusion point of the diabase 
was lowered by mineralizers at the time of the intrusion. 
SPETHMANN, Hans. Islands grosster Vulkan. Die Dyngjufjoll mit 
GCA Shia: LeIpzigs) Vieltatw) CO... 10038) Vi Ep. ran, ese i260) 
bibliography. 
The author gives first a summary of work previously done in this 
region, including an account of von Knebel’s ill-fated expedition. He 
then tells of the development of the maps of this region, describes the 
forms of relief, the climate, and the vegetable and animal life. 
The volcano Dyngjufjoll les east of the central part of Iceland. 
Its crater, Askja, is the largest in the island, and has a fairly flat bottom 
of from 55 to 60 square kilometers. In the southeastern portion of this 
crater bottom is a lake, Knebel Sea, covering about one-fifth of the area, 
and at its northeast shore is an active crater, Rudloff Crater. South- 
west of the lake is a solfatara field. The mountain owes its origin to 
volcanic eruptions from a conduit within the area of Askja. The material 
ejected was fragmental, but later was followed by a lava flow which 
filled the cauldron with a sea of lava and caused overflows at several 
points. There were various fluctuations of the surface of this flow, the 
last one being a sinking of the level from 40 to 50 meters. In January 
and March, 1855, there were eruptions of fragmental materials, and at 
the same time several large areas of the crater bottom, near the Knebel 
Sea, settled and filled with water from this lake. 
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