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SCIENCE 



[N. S. Vol. XXVI. No. 659 



reading-room in Christiania, for a complete 

 catalogue of the literature of internationalism, 

 a school, the printing of books and periodicals 

 and the establishment of another arbitration 

 court. These are highly creditable projects, 

 but the Nobel Fund was given for another pur- 

 pose. All the countries of the world have the 

 same interest in it as Norway and Sweden, 

 and they have a right to protest against its 

 misappropriation. — The Independent, May 9, 

 1907. 



CURRENT NOTES ON LAND FORMS 



PIT CRATERS IN MEXICO 



Among the many basins of the Central 

 Plateau of Mexico, bordered by volcanoes in 

 various stages of growth and dissection, and 

 smoothly floored with aggraded layers of vol- 

 canic ashes and dust, of fluviatile and lacus- 

 trine desposits, and of occasional lava flows, 

 there is one of typical development in the 

 state of Puebla, east of the city of Mexico and 

 separated by the volcano of Orizaba and its 

 neighbors from the dissected escarpment by 

 which the descent is made from the highland 

 to the coastal lowlands. Ordonez gives a good 

 account of this basin-plain and of the pit 

 craters that have been formed in it by ex- 

 plosion (" Los Xalapaseos del Estado de 

 Puebla," Inst. Geol. Mex., Parerg., i, 1906, no. 

 9). The plain is like all its fellows in having 

 risen on the irregular flanks of the larger and 

 smaller, younger and older volcanic masses 

 that enclose it, and in being interrupted by 

 more or less completely isolated volcanic 

 knobs and ridges which rise here and there 

 through its smooth surface. The gentle as- 

 cent by which one ordinarily approaches the 

 border of an explosion crater is an insignif- 

 icant element of relief in comparison with the 

 much larger volcanic forms on all sides; in- 

 deed, the slope is sometimes hardly perceptible, 

 and the depression of the crater, 1,000 to 

 1,800 met. in diameter, and 50 or more,.met. 

 deep, is come upon as a surprise for which 

 there is no warning at a little distance. A 

 shallow blue 'lake usually occupies the floor; 

 the walls are frequently steep and expose good 

 sections of the layers by which the plain has 

 been built up; special interest attaching to 



such items as buried stream channels and oc- 

 casional thin lava sheets. Paths lead down in 

 zigzags on the steep face or more directly by 

 centripetal ravines; for the poor natives in 

 neighboring villages have long been accus- 

 tomed to carry water up from the lakes for 

 domestic uses. Ordonez regards these craters 

 as among the latest manifestations of volcanic 

 activity, and characterizes them as seeming 

 unduly large for the feebleness of the explosive 

 force which produced them. 



BATOKA GORGE OP THE ZAMBESI 



Among the results of the British Associa- 

 tion visit to South Africa in 1907 is an ac- 

 count of " The Geology of the Zambesi Basin 

 around the Batoka Gorge," by G. W. Lamp- 

 lugh (Quart. Journ. Geol. Soc, LXIII., 1907, 

 162-316), which includes an excellent descrip- 

 tion of a plateau in a youthful stage of dis- 

 section. In the region of Victoria Falls, the 

 South African highland is built up of basalt 

 sheets ; older rocks, including a fundamental 

 complex of gneiss, schists and granite, appear 

 to the northeast and southeast. The relief is 

 small; occasional residual knobs — Inselherge 

 of the German explorers — rise here and there 

 in the crystalline areas ; low escarpments tra- 

 verse the belts of inclined strata bordering the 

 crystallines; broad swells of sand, supposed to 

 be wind deposits of an earlier and more arid 

 period, are spread over the basalts. The 

 present altitiide of the plateau is 3,000 feet 

 or more. The upper Zambesi is a wide, placid 

 river flowing through a shallow valley, bor- 

 dered by low slopes of greatly decomposed 

 basalt; its branches are of gentle fall and 

 their valleys (called " channels " by Lam- 

 plugh) are but little below the general high- 

 land level. At Victoria Falls, the river 

 plunges down 360 feet into a narrow gorge 

 with nearly vertical walls, in which the pecu- 

 liar zigzag turns have been well explained by 

 Molyneaux (" The Physical History of Vic- 

 toria Falls," Geogr. Journ., XXV., 1905, 40- 

 55) as the result of groups of obliquely trans- 

 verse joints. In 60 miles below the falls, the 

 river descends about 400 feet, and the walls of 

 the gorge become more and more open. At the 

 same time, the side gorges increase in length. 



