J. F. Kemp — Extension of the Cortlandt Series. 247 



reason to suppose that plant-roots derive their food only from 

 the finest sediments with the help of carbonic and weak organic 

 acids. Therefore, extraction with hydrochloric acid does not 

 reproduce or represent the processes which are going on in 

 nature. 



4. The fertility of a soil greatly depends not only upon the 

 quantity of phosphoric acid which is present, but also upon 

 the mode of its occurrence. We are unable to ascertain with 

 accuracy with what bases the phosphoric acid is combined in 

 the soil ; we are further utterly unable to find out if the con- 

 ditions for transformation of the insoluble phosphates into 

 soluble ones are favorable in any given soil. 



5. Therefore, it is not possible to decide about the fertility 

 of a soil on the strength of a chemical analysis. As an excep- 

 tion, however, I must mention certain desert- soils. If chemi- 

 cal analysis should reveal that such a soil consists almost en- 

 tirely of silica, we can with good conscience predict to the 

 farmer very poor harvests. 



I do not profess to have brought forward any new facts. I 

 believe to have only confirmed by my work opinions which 

 were expressed already long ago by authorities in the domain 

 of agricultural chemistry. As chemical soil-analysis is still car- 

 ried on in America and in Europe, often, it must be acknowl- 

 edged, with industry and laudable perseverance, I thought it 

 to be my duty to communicate my results, however modest 

 and fragmentary they may be, to my fellow workers, with the 

 hope to prove myself useful to them. 



1887. Berkeley, Cal. 



Art. XX Y. — On the Bosetown Extension of the Cortlandt 

 Series ; by J. F. Kemp. 



In the fieldwork of the New Jersey Survey of 1885,* Dr. N. 

 L. Britton and Mr. F. J. H. Merrill came upon evidences of 

 what appeared to be a further extension of the well known 

 Cortlandt seriesf on the Hudson River. They were due west 

 of Stony Point, about the small cross-roads settlement known 

 as Rosetown. The observations were suggested to the writer 

 and by him the following results have been worked out so that 

 the Rosetown area is now definitely circumscribed. 



As will be seen from the accompanying map it extends in an 

 irregular shoe- shaped outline with its longer axis running ap- 



* Ann. Bep. N. J. State, Geol. 1836, p. 70; School of Mines Quarterly, vol. ix, 

 p. 33. 



f This Journal, III, xx, p. 194. 



