GEOLOGY. 265 



Litliographic Researches. — Geologists will be much interested in 

 the reported discovery of Dr. Jenzsch, of Gotha. This savant^ 

 it is said, has devoted himself for some years to what he calls 

 microscopic lithographic researches, and now announces that in 

 various kinds of crystalline and volcanic rocks he has discovered 

 minute animal forms in prodigious numbers, and in a fossil condition. 

 Some of the creatures he describes as having been petrified in 

 the midst of their "life functions." Among them, he finds Infu- 

 soria and Rotiferce, intermingled with Algce, and he mfers their 

 formation in a large expanse of stagnant water. 



The Colorado Expedition. — The expedition under the command 

 of Col. Powell, the Colorado explorer, has returned to Chicago, 

 having successfully travelled through the entine Grand Caiion, 

 from Green River to the point where the Colorado debouches into 

 the open plain, in the territory of Arizona. 



Fi'om the point where Colonel PowelPs last letter was written, 

 the expedition descended the river about 400 miles, between 

 walls almost vertical, ranging from 500 to 1,500 feet high, the 

 exterior of the canon being from 2,500 to 4,000 feet above the 

 bed of the river. More than 200 waterfalls and cascades, 

 emptying themselves over the walls of the canon into the main 

 river, were seen in this distance, with almost every variety of 

 natural scenery. The geological formation of the canon consists 

 principally of limestone and sandstone ; granite is only found at 

 three places, and in a limited amount. No discoveries of 

 precious metals were made, and there were no indications of 

 gold or silver found in the bed of the river. 



One section of the canon was found to consist of a very fine, 

 beautifully polished marble, which at present is entirely inacces- 

 sible. The country traversed was barren beyond description, and 

 is pronounced by Colonel Powell as not susceptible of cultivation, 

 even by irrigation. 



Effect of Irrigation. — The Suez Canal appears likely to pro- 

 duce a radical change in the climate of the surrounding country. 

 From a series of meteorological observations made during two 

 years at three different stations on the isthmus, we are led to 

 infer the interesting fact that introduction of the waters of the Med- 

 iterranean into the lakes has caused an atmospheric moisture in 

 places herotofore noted for their dryness, to such an extent that 

 fogs, equal in intensity to those of some European cities, now 

 occur. This appears to support an important conclusion of Colo- 

 nel Foster, in his recently published work, with regard to the 

 eflfect that irrigation would have on our western deserts. 



Durangite. — The mineral is of a bright orange-red, the ciys- 

 tals having a rhombic aspect ; streak, cream-yellow ; lustre, vit- 

 reous ; cleavage, distinct in two directions ; crystallizations, mon- 

 oclinic; hardness, 5; specific gravity, 3.95 — 4.03. The small 

 quantity which could be used for the test did not allow a full 

 and complete quantitative determination. Direct duplicate estima- 

 tions, however, were obtiiined of every constituent, except fluor- 

 ine. This last element was Ibund to exist in such considerable 

 quantity, that the fluohydric acid evolved in attacking the mineral 



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