178 



SCIENCE. 



[N. S. Vol. XXIV. No. 606. 



My interpretations were influenced by what 

 seemed to me negative evidence both in topo- 

 graphic forms and in surficial materials 

 throughout the lower ranges and intervening 

 plains of western Sonora and southern Ari- 

 zona. I have ridden over and camped on the 

 country between Arivaea and Sopori (men- 

 tioned by Dr. Merrill), where the erosion 

 forms assumed by the widespread tuff bed's 

 often simulate morainal deposits in general 

 landscape effects, without finding indications 

 of glacial agency either in deposits or in 

 m.inute topography; while over the more ele- 

 vated remnants of eroded ranges and among 

 the lower slopes of the more rugged sierras 

 most of the topographic forms impressed me 

 as not merely water-cut but carved in that 

 peculiarly acute fashion characteristic of the 

 margins of sheetflood plains. Some of these 

 plains are indeed diversified, especially toward 

 the mountain margins, with both basin-shape 

 depressions and debris-heaps, the latter fre- 

 quently near the valleyward extremities of the 

 former — the basins having been originally 

 places of concentrated flow of the (generally 

 dwindling) sheetfloods, and the debris-heaps 

 the delta-like accumulations by which the 

 localized corrosion was originally checked; 

 though the heaps usually outlast the basins, 

 especially when composed largely of obdurate 

 rock-fragments, and form a type or genetic 

 class of those natural mounds which are of 

 late attracting much attention. The region is 

 one of distinctively significant geomorphy; 

 for it is not only the type district of sheetflood 

 erosion, but comprises an extensive area of 

 retrogressive carving due to a southwestward 

 tilting — an area in which the general divides 

 seldom coincide with the axes of the sierras 

 but run far out on the low-lying plains be- 

 tween, circumscribing the head slopes of 

 waterways (of which Rio Seco and Rio Bacu- 

 ache are types) that have retrogressed north- 

 eastward entirely through the ranges in which 

 they originally headed. Several examples of 

 this remarkable retrogression were surveyed 

 and mapped in detail by Willard D. Johnson 

 in connection with that expedition which 

 yielded his notable map of Seriland published 

 in the National Geographic Magazine and also 



in the Seventeenth Annual Report of the Bu- 

 reau of American Ethnology; unfortunately, 

 these surveys have not yet been published. 

 During this same expedition Mr. Johnson 

 worked over most of the surface and ascended 

 most of the crests along the valleys lying next 

 west of that of the Imuris; but neither he nor 

 I noted ice-shaped topography anywhere in the 

 region. Of course, any negative inference is 

 worth far less than the positive inductions of 

 a geologist familiar, like Doctor Merrill, with 

 such glacial topography and deposits as those 

 of northeastern United States ; yet it is worthy 

 of consideration pending more extended sur- 

 veys than have thus far been found practicable 

 in the Sonoran province. 



W J McGee. 

 Saint Louis Public Museum. 



THE EARTHQUAKE AND PROFESSOR LARKEN. 



In the Open Couri for July, 1906, is a re- 

 markable account of ' The Great San Fran- 

 cisco Earthquake,' from the pen of Edgar L. 

 Larkin, of the ' Lowe Observatory on Echo 

 Mountain,' otherwise professor of astronomy 

 and geology in the University of the Sunday 

 Supplement. 



Professor Larkin came to San Francisco 

 immediately after the earthquake of April 18. 

 In a day or two he was able to discover a 

 number of things which had escaped the notice 

 of the local geologists, Lawson, Branner, Gil- 

 bert, Campbell, Davidson and others, consti- 

 tuting the official State Earthquake Commis- 

 sion. 



Professor Larkin says : " One of my objects 

 in leaving the peace and quiet in the observa- 

 tory on the mountain, to make a five-hundred- 

 mile journey to the stricken city, was to study 

 the action of the earthquake in the great 

 cemeteries. The fallen columns write the 

 history of the convulsion in stone." To his 

 surprise he found that " the half dead made 

 their homes with the dead. Weak and wan 

 girls played with the marble angels. * * * 

 One desolate family found shelter in a beauti- 

 ful sepulchre while the sufferers rested their 

 heads on lowly graves." This was the more 

 remarkable, for, as Jerome Hart suggests in 

 the same connection, there is in California a 



