March 17, 1916] 



SCIENCE 



399 



type was designated a grooved upland, since the 

 glacial troughs heading in semicireular cirques in- 

 vade the upland. The opposite extreme, in which 

 the entire inherited surface has been destroyed 

 through glacial sculpture, was termed a fretted 

 upland for obvious reasons, and the Alps cited as 

 the type example. The characteristic of this type 

 of upland — the Sierra — consists in main lines of 

 palisades, or comb-ridges, from which lateral spurs 

 of palisades diverge at frequent intervals. The 

 general dominance of this type of topography in 

 most regions where mountain glaciers have been, 

 would seem to imply that mountain glacial sculp- 

 ture proceeds with great rapidity through the en- 

 largement and extension of the cirque; and that, 

 further, this process is slowed down so soon as the 

 pre-glacial upland has been removed. Otherwise 

 we should expect that cols, or passes carved by 

 eirqne extension, would be much lower than they 

 are. 



A more extreme ease of glacial sculpture seems 

 to be illustrated by the northern Eocky Mountains, 

 particularly within the Glacier National Park. 

 Here in place of the comb-ridges, so characteristic 

 of the fretted upland, we find an abundance of 

 monument-like peaks, not the true horns merely 

 within the fretted upland, but lower eminences 

 which seem to have resulted from progressive low- 

 ering of the cols and the consequent coming into 

 prominence of the broader parts of the comb 

 ridges at either side of the entrance to the cirque 

 from the U valley. This type of upland, an ex- 

 treme product of mountain glacial erosion, we may 

 designate a monumented xipland. That the Big- 

 horn range of Wyoming and the Glacier National 

 Park thus present the extremes of mountain glacial 

 erosion, was confirmed by studies which were car- 

 ried out upon the ground in both districts during 

 the summer of 1915. 



The Earthquake in the Imperial Valley on June 



22, 1915: "W. H. Hobbs. 

 Outliers of the Maaville Limestone in Ohio, North 



of the LicMng Eiver: G. F. Lamb. 

 A Giant Pot-hole near Scranton, Pennsylvania: 



H. N. Eaton. 



The pot-hole in question is located about seven 

 miles northeast of Scranton, Pa., in the ravine of 

 a small stream on the southern side of Bald Moun- 

 tain, 340 feet above the Lackawanna Eiver. It is 

 known to local naturalists and mining men on ac- 

 count of its great size, having a width at the top 

 of 34 feet and a depth from the top to the debris 

 at the bottom of 29 feet. The original depth was 



probably much greater. The bed rock is a gently 

 dipping sandstone of a lower horizon of the Coal 

 Measures. The origin of the hole by rotary 

 abrasion is evident from its contour as shown in 

 the photographs. Fluted and scoured rock sur- 

 faces in the immediate vicinity afford ample evi- 

 dence of violent stream work, and although the 

 glacial history of the region is not fully known it 

 is probable that the pot-hole was formed by a 

 stream issuing from the melting ice. » 

 A New Occurrence of Crystallized Willemite: R. 

 W. Clark. 



The willemite occurs in the Star District, Beaver 

 County, Utah, in drusy masses of small crystals, 

 which are sometimes colorless and sometimes red 

 due to dilute coloring matter. It is associated 

 with hemimorphite, calcite, mimetite, quartz, cefus- 

 site and limonite. The crystals show the following 

 forms: c(OOOl), e(0112), a(1120), m(lOlO). 

 The indices of refraction determined under the 

 microscope by the immersion method are 

 e=z 1.716, w = 1.690. 



The Girdled Mountain: A Direct Consequence of 

 General Desert Erosion: Charles Kbyes. 

 For the development of those rock-floored pied- 

 monts which so often are characteristic of many 

 arid regions there is an explanation much simpler 

 than that usually given — one that is more in ac- 

 cordance with recent advancements in our knowl- 

 edge of desert erosion. It does away with all of 

 the assumptions necessarily arising out of the 

 adoption of the old hypothesis which postulates 

 prodigious valley-fill, and an uncovering by moun- 

 tain freshets of an ancient bed-rock surface of the 

 shallow margins of the interment spaces. This 

 old hypothesis had its foundation in the impres- 

 sion that the interment plains are aggraded tracts 

 instead of surfaces now undergoing rapid degra- 

 dation, and that the agency is stream-corrasion 

 much the same as in humid climates except per- 

 haps somewhat less vigorous. The phenomenon is 

 now believed to be one of the minor expressions of 

 eolic erosion on that part of the orographic block 

 which suffers maximum abrasion through natural 

 sand-blast action. Many lofty desert mountains 

 are thus deeply girdled just above the level at 

 which the general plains surface meets them. 

 The Origin of the Coarse Breccia in the St. Louis 

 Limestone: William C. Morse. 

 At least two kinds of breccia are present in the 

 St. Louis limestone, one fine and the other coarse. 

 The fine breccia is, in many cases, confined to a 

 layer, or to two or three layers, at one or different 



