374 



SCIENCE. 



[N. S. Vol. II. No. 38. 



subject in Eussell's Geological Survey Mon- 

 ograph on Lake Labontan. Besides sev- 

 eral figures, it contains a general map, 

 showing the areas of present and extinct 

 lakes, and three maps of larger scale, one 

 of which ft-om surveys by W. D. Johnson 

 exhibits certain details of extinct shore- 

 lines with great nicety. All the illustra- 

 tions are, however, only reproductions of 

 those alreadj^ published in the survey mon- 

 ograph above mentioned, and thus have 

 less freshness than new illustrations would 

 have. 



The fifth monograph is on the ' Beaches 

 and Tidal Marshes of the Atlantic Coast ' 

 by Professor E". S. Shaler, of Harvard Uni- 

 versity. This is for the most part occupied 

 with an account of shore processes rather 

 than shore forms, and is in onlj^ a second- 

 arjr way concerned with the Atlantic Coast. 

 Unfortunatelj', it has no illustrations, and 

 the number of specific examples of shore 

 forms, described ready for teachers' use, is 

 comparativeljr small. It seems too much to 

 call our oil-shores and-bars ' indestructible 

 shields ' of the continent ; and to say that 



upon them the 'ocean waves break 



without eifect.' 



The sixth monograph, on the ' ISTorthern 

 Appalachians,' by Bailey Willis, of the U. 

 S. Geological Survey, contains a greater 

 amount of new matei'ial and new presenta- 

 tion than the two preceding numbers. The 

 region between the Blue Eidge on the east 

 and the Alleghany front on the west is 

 called the ' Greater Valley,' in distinction 

 from the ' Great Valley ' of general usage, 

 which does not include the ridge-and-valley 

 area west of the slate and limestone low- 

 land. The general lowland level of the 

 Greater Valley is described as a surface of 

 denudation, and is called the Shenandoah 

 ' base-level; ' the ridges rise above it, not yet 

 worn down ; the streams traverse it in 

 trenches, excavated since a moderate uplift 

 of the region. The ancient surface, of 



which the even uplands and the level crest 

 lines of the ridges are remnants, is called the 

 Kittatinny ' base-level; ' this is also recog- 

 nized as a peneplain, but of ancient date, 

 and now much dissected by the excavation 

 of the valley floors. The three chief divis- 

 ions of the region ' constitute a group, in 

 which the Blue ridge may be called a con- 

 tinental range; the Greater Valley a tilted 

 literal zone ; and the Alleghany front, which 

 confronts the old continent of Appalachia, 

 an inland-facing 'fescai'pment.' [' Inface ' 

 has lately been suggested as a more com- 

 pact name for the last mentioned topo- 

 graphic form.] The Shenandoah is shown 

 to have gained length by diverting to its 

 own course the headwaters that once be- 

 longed to Beaver Dam creek; Snicker's Gap 

 in the Blue Ridge representing the former 

 outlet of the now diverted headwaters, and 

 the beheaded creek now rising on the east- 

 ern slope of the ridge. 



THE COMPOSITE ORIGIN OF TOPOGRAPHIC 

 FORMS. 



Under the above title Prof. A. P. Brig- 

 ham has contributed an essaj^ to the Bul- 

 letin of the American Geographical Society 

 (XXVII., 1S95, 161-173) in which he 

 brings together a number of illustrations of 

 the various processes, constructive and de- 

 structive, by which the forms of the land 

 are assumed. He emphasizes the impor- 

 tance of this aspect of geographical study : 

 " The teacher of physiography has no 

 greater reward than is his where a student 

 assures him that henceforth his native State 

 will be to him a new country, or that he 

 will see the hills and vallej^s of his old home 

 with new ej'es Eveiy journey be- 

 comes fi-aught with meaning, and the trav- 

 eller who has caught the spirit of modern 

 geographj' will not report the great plains 

 of Kansas and Nebraska as ' uninteresting.' 

 It must, however, still be said that many 

 colleges deny their graduates this appreci- 



