96 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES. 



alone," and it was at this period that the principal islands of Southern Cali- 

 fornia were brought above sea. 



Professor Ritter, of the San Pedro Marine Biological Station, has 

 recently contributed an interesting article to Science on the work of that 

 well conducted institution, in which he refers to one of these submerged 

 valleys, possibly a part of the former course of the Los Angeles river or the 

 San Gabriel river. The fact of the existence of these old channels is well 

 known to geologists and Professor Davidson's valued contributions to the 

 subject are held in high esteem. As LeConte sagely remarked in the paper 

 quoted above:! " It is impossible to conceive a more inviting field for the 

 study of the higher problems of geology than is aflForded by the phenomena 

 of the liver-beds of California " 



We have here in IvOs Angeles a beautiful piece of river carving, as 

 exhibited in the gorges of the Los Angeles River and Arroyo Seco. Fine 

 sections and very instructive erosion etchings are also afforded by Ihe 

 canons reaching the sea through the Santa Monica Mountains, Irom Port Los 

 Angeles westward to Point Duma. These are particularly- mentioned because 

 they elucidate paragraphs in the later chapters of the geologic volume, j 



It is to the interest, and an important part of the dutj-, of our Academy 

 of Sciences to enlist young people in the studj' of these phenomena. Let us 

 organize field work in the Geological Section as early as possible in the 

 autumn, and, meanwhile, consider it your individual work to gather earnest 

 students into this organization .From Archceanto Recent, the whole record 

 is within easy travel of this city and. actually, we ourselves are the very 

 most ignorant of the meaning of it all. 



Messrs. Delos and Ralph Arnold have published (Feb. -March, 1902) 

 in the Journal of Geology some of the results of their work on "The Marine 

 Pliocene and Pleistocene Stratigraphy of the coast of Southern California." 



Professor R. E. Dodge presented a timely paper on "Arroyo Formation" 

 before a late meeting of the N. Y. Academy of Sciences, in which he gives 

 a caution against too explicit reliance on a single factor in interpreting the 

 rate of erosion or deposition in arid regions. It is peculiarly difficult to 

 correlate separated deposits and to assign time-values in our Pleistocene 

 terraces and silted channels. Generalizations not based on very exact data 

 or cumulative evidence are untrustworthy and can only be adopted tenta- 

 tively. 



The recent discovery of the remains of extinct Mammals in Quaternary' 

 deposits in the city of Los Angeles makes probable the unearthing of others 

 which may have great value in settling points of local geology. It often 

 happens, as in this particular case, that the bones, tusks and other parts are 

 soft or crumbling. It is possible to handle these in such manner as to 

 prevent their loss and to preserve them intact, if the aid of some one familiar 

 with the work is secured in time. In all such cases, before the workmen 

 are permitted to disentomb the relics, word should be sent to the President 

 of the Southern California Academy of Sciences, office 534 Stimson Building, 

 who will be ready to superintend the excavation in the interest of Science. 

 Public spirited owners of such specimens will donate ^hem to the Academy 

 for preservation; but, at any rate, give us a chance to make observations 

 and to ensure the relics against irreparable damage. 



f Tertiary and Post-Tertiary Changes of the Atlantic and Pacific Coasts. Bull. Geol. Soc. 

 Amer., Vol. 2, p. .32.3-328, March, 1891. 



JUiider date of June 24th, 1902, Professor Davidson writes me that there have been 

 "noted on recent charts two orniore such vallej's on the West coast of South America." 



