MISSISSIPPI AND LOUISIANA GEOLOGICAL SURVEYS 171 



soils, water supply, and marls. In the prosecution of these studies the 

 close connection between the surface vegetation and the underlying for- 

 mations became so striking that he was soon largely able to avail himself 

 of this vegetation in tracing out the limits of adjacent formations and in 

 searching for outcrops. 



In our studies of the Coastal Plain of Alabama your present speaker 

 and his associate, Daniel W. Langdon, have time and again found that 

 this method of geologizing is by no means to be neglected or held in slight 

 esteem. 



In the 1860 report, about evenly divided between agricultural and 

 geology, chemical analyses of typical soils of the several agricultural re- 

 gions are given, along with discussions and estimates of their cultural 

 value as indicated by these analyses considered in connection with the 

 native vegetation. Hilgard's later studies of these relations, carried out 

 in the preparation of the Cotton Culture Eeports of the Tenth Census, 

 and during many years of research in California, seem to have established 

 the right of soil analysis to be considered as an essential and often de- 

 cisive factor in the estimation of the cultural value of virgin soils. 



The geological half of the report presents the geology of Mississippi 

 practically as it is known at the present day, except as to the fixing of 

 the age of the Port Hudson beds, as below mentioned, and the investiga- 

 tion of the geology of the Mississippi bottom from Memphis to Yazoo 

 City, and the tracing of the Lower Claiborne formation westward to the 

 border of this bottom. The two latter were assigned to me and carried 

 out in 1870 and 1871. These additions and revisions are shown on a map 

 of Mississippi published by T. S. Hardy, state engineer, in 1872, and 

 reproduced, with some slight changes, in the map accompanying the 

 report of Eckel and Crider in 1907.^^ 



In 1867, under the auspices of the Smithsonian Institution, and in 

 1869, under the auspices of the N"ew Orleans Academy of Sciences, oppor- 

 tunity was given to Doctor Hilgard to extend his researches down the 

 Mississippi Eiver to the passes and through Louisiana in a thirty-day 

 reconnaissance trip. In these excursions the post-Pliocene age of the 

 Port Hudson '^stump stratum" and, by inference at least, its extension 

 from the Sabine River to Mobile Bay were definitely determined, and the 

 Coast Pliocene of the 1860 map was changed to Port Hudson. The re- 

 sults of these expeditions may be summarized as follows : 



1. The outlining of the Mississippi Embayment in Louisiana and 

 Mississippi. 



Mississippi Geological Survey, Bulletin No. 1. 



