140 



SCIENCE 



[N. S. Vol. XLVI. No. 1180 



light of an unconformity, the interval repre- 

 sented being a stage between two high water 

 marks when the old lake-waters completely 

 dried up. Early BonneviUe yellow beds are 

 correlated in time with a first epoch of humid- 

 ity superinduced by conditions of glaciation; 

 while the white later Bonneville beds belong 

 to the second Glacial epoch. The two parts of 

 the section are thus represented as being sep- 

 arated by an erosional interval of long dura- 

 tion, occupying a time between two epochs of 

 large rainfall and notable ice-forming. 



Two features in particular militate strongly 

 against these deposits either being normal 

 stream-silts or being laid down during two 

 distinct epochs separated by a long epoch of 

 excessive dryness. This simpler and very dif- 

 ferent interpretation for the phenomena pre- 

 sented does not postulate violent and frequent 

 changes of climate. It appeals to no other 

 than the ordinary climatic conditions and 

 geologic processes that prevail to-day in the 

 region. It takes into account only the famil- 

 iar geological activities of the desert. 



Close examination of the deposits discloses 

 the fact that they are not typical stream-silts, 

 but that they have a grain very much coarser. 

 In size the individual particles appear to be 

 about midway between those of normal clay 

 and fine sand. Although obscurely laminated 

 the material in all physical aspects seems to 

 be essentially loess or adobe. Thus, instead 

 of being normal river-silts swept into still 

 water these deposits really represent dusts, 

 borne by the winds from the neighboring 

 deserts, that have dropped on the surface of 

 the lake waters and have settled to the bottom. 



Compared with desert deposits of other re- 

 gions the white marly upper beds of the sec- 

 tion which have such a variable thickness are 

 essentially what the Mexicans call caliche. 

 It is formed through ordinary soil tension by 

 which lime salts of porous formations below 

 are carried to the surface of the ground, where 

 the water evaporates, leaving behind the solids. 

 In some places there is sufficient lime de- 

 posited interstitially to give the beds the as- 

 pect of chalk. Upon further induration some 

 layers passed into limestone. 



The juncture of the yellow and white beds 

 is a sharp, irregular line that is easily mis- 

 taken for an erosion uncomformity. That it 

 is not at all probable that in the Bonneville 

 basin this line actually represents vmcomform- 

 able relationships between the beds above and 

 those below is clearly indicated by the fact 

 that the phenomenon is a common one through- 

 out arid lands where porous formations reach 

 sky. 



The yellow Bonneville clays do not appear, 

 therefore, to represent a deposit which was 

 laid down during a high-water precursor of the 

 high-stage Lake Bonneville; and the irregular 

 line separating the yellow and white sections 

 does not stand for a long interlacustrine epoch 

 when the lake waters were completely desic- 

 cated, during a dry interglacial time. The 

 white marls seem to be very recent in forma- 

 tion, produced directly from the yellow clays 

 long after Bonneville waters had finally re- 

 ceded. Their especial climatic significance 

 is manifestly very diiferent from that formerly 

 postulated. The ascribed peculiarities are 

 really every-day desert phenomena. 



Charles Keyes 



Des Moines, Ia. 



INTERNAL TELIA OF RUSTS 



To THE Editor of Science : A recent article^ 

 lists up the references in j)athological litera- 

 ture regarding the production of internal rust 

 spores. The present writer in 1912^ described 

 such internal production of teliospores in the 

 leaf of Xanthium Canadense, in the following 

 words : 



Within the mixture of parenchyma cells and 

 mycelium, which replaces the normal tissue, there 

 are cystUke bodies which are composed of masses 

 of mycelium. These objects are hollow spheres, 

 and from the inner surface arise teUal spores ex- 

 actly similaj to those borne in the normal way 

 upon the exterior of the leaf. 



1 "Discovery of Internal Telia Produced by a 

 Species of Cronartium," by R. H. Colley, Jour. 

 Agr. Besearch, VIII., No. 9, February 26, 1917, 

 pp. 329-332. 



2 ' ' Relations of Parasitic Fungi to their Host 

 Plants," Bot. Gasette, LIU., No. 5, May, p. 381. 



