68 



SCIENCE. 



[N. S. Vol. XVI. No. 393. 



some reason must be sovight for tlie large 

 number other than mere coincidence or the 

 fact that the area is not forested. A further 

 feature of interest in connection with the fall 

 is the fact that it occurred at the time of the 

 Leonid showers. Only two such instances 

 have hitherto occurred within this period, 

 these two being the falls of Werehne Tschir- 

 skaja and Trenzano. These are both veined 

 spherical chondrites and the present indica- 

 tions are that Saline Township belongs in the 

 same category. 



Olher C. Farrington. 



notes on the lafayette and columbia forma- 

 tions and some of their botanical 

 features. 



Having spent considerable time during the 

 past two years in making a critical study of 

 the flora of Georgia in all its aspects, I have 

 been investigating, among other things, the 

 influence of geological conditions on the pres- 

 ent distribution of species. The most striking 

 relations between geology and existing flora 

 have been observed in the coastal plain, and 

 I have restricted my explorations chiefly to 

 that part of the state in order to study the 

 interesting problems there presented. 



The existing knowledge of the areal geology 

 of the coastal plain is much less complete in 

 Georgia than in the adjacent states, partly 

 because the energies of the State Geological 

 Survey have hitherto been necessarily devoted 

 mostly to the investigation of mineral re- 

 sources and other questions of more imme- 

 diate economic importance, and partly because 

 Georgia has for many years been singularly 

 neglected by geologists and other scientific 

 people. This state of afl'airs has been a source 

 of considerable difilculty in the prosecution 

 of my work, and has led me to undertake 

 some geological investigations on my own 

 account, most of those on which these notes 

 are based having been made during the sum- 

 mer of 1901. 



My geological observations have thus far 

 been mostly confined to the Lafayette and 

 Columbia formations, which as they cover 

 almost the entire surface of the coastal plain 

 are the most easily accessible, and at the same 



time are quite readily recognized even by an 

 amateur like myself. My knowledge of these 

 formations, aside from my work in the field, 

 has been chiefly derived from Mr. W J Mc- 

 Gee's monograph in the Twelfth Annual Ee- 

 port of the IT. S. Geological Survey, and from 

 consultation and correspondence with Mr. 

 McGee himself; and it was at his suggestion 

 that I undertook to prepare these notes for 

 publication. 



In addition to the ordinary way of study- 

 ing geological formations by their exposures 

 in natural or artificial excavations, I have 

 employed in the case of the Lafayette and 

 Columbia, with very satisfactory results, an- 

 other method which has perhaps never before 

 been utilized to any considerable extent. This 

 method consists in identifying the formations 

 by means of the plants growing upon them. 

 Early in the course of my investigations I 

 noticed that certain species of herbaceous 

 plants seemed to occur only on the Columbia 

 sands, and that it made considerable differ- 

 ence in the distribution of some other species, 

 especially trees, whether the Lafayette clays 

 were present beneath the Columbia or not. 1 

 then used these species as an index in deter- 

 mining the formations when the regular 

 method could not be used for lack of suitable 

 exposures or when traveling by rail. This 

 method should not be depended upon alto- 

 gether, but when used with due caution it is 

 very helpful. 



I will mention here some of the more con- 

 spicuous plants which have served thus to 

 indicate the formations, and would suggest 

 that it would be advisable for every geologist 

 who studies the Lafayette and Columbia for- 

 mations in the southeastern states to familiar- 

 ize himself with as many of these plants as 

 possible. 



The best indicator of the Columbia forma- 

 tion which has come under my observation is 

 Eriogonum tomentosum, a plant which when 

 in flower, in late summer, grows three or four 

 feet tall and is conspicuous and unmistakable. 

 It ranges from South Carolina to Florida and 

 Alabama, and is widely distributed in the 

 coastal plain, extending up to its inner margin 

 at altitudes of six hundred feet or more. 



