AMERICAN GEOLOGY DECADE OF 1860-1869. 535 



of the Tertiary as distinct from the Orange sand, this latter name 

 having been originally provisionally applied by him to a series of 

 strata which he regarded as, for the most part, equivalent to Hilgard' s 

 northern lignitic. The general grouping of the formations, from the 

 Cretaceous upward, was essentially the same as had been given by 

 him in a previous paper in the American Journal of Science (1861), 

 and which is as follows, beginning at the bottom: 



1. Coffee sand Cretaceous. 



2. Green sand or the shell bed Cretaceous. 



8. Ripley group (provisional ) Cretaceous. 



4. Porter's Creek group (provisional) Tertiary (?) 



5. Orange sand or Lagrange group Tertiary. 



6. Bluff lignite (provisional) Tertiary (?) 



7. Bluff gravel Post-Tertiary. 



8. Bluff loam '. Post-Tertiary. 



9. Bottom alluvium Modern. 



Fifteen new species of invertebrate fossils were described. The 

 work does not seem to have attracted much attention at the time, and 

 was given but a half-page review in the American Journal of Science 

 for that year. In this, attention was merely called to the fact that Saf- 

 ford differed with Hilgard on the question of the age of the Orange 

 sand. 



In 1869 E. W. Hilgard, acting under the auspices of the New Orleans 

 Academy of Sciences, made a reconnaissance of Louisiana, a summary 

 of the results of which was published in the American Journal of Sci- 

 ence for 1869. The expense of the trip was paid partly 

 LouUifna .^s^. 111 by subscription and partly by an appropriation by the 

 State Board of Immigration, and the time limited to 

 thirt} 7 days. The journey (some 625 miles) was made mainly on horse- 

 back, passing Petite Anse and New Iberia on the Teche by way of 

 Opelousas to Bayou Chicot; thence to the Calcasieu River, down that 

 stream to Lake Charles and the sulphur and petroleum wells, on the 

 West Fork of the Calcasieu River; thence north to Sabine Town, Texas; 

 thence by way of Many to Mansfield, Louisiana; thence, crossing Red 

 River at Coushatta Chute landing to the salines on Saline Bayou, and 

 thence, by wa} T of Winnfield and Harrisonburg on the Ouachita River, 

 where the expedition terminated. Among the more striking results 

 announced was the fact that the Gulf coast has in late Quaternary 

 times suffered a depression to the extent of at least 900 feet, and dur- 

 ing the Terrace epoch a contrary motion to the extent of about half 

 that amount. The occurrence of sulphur and gypsum beds was also 

 noted. The various formations were described as: The Port Hudson 

 group, the Orange sand formation, the Grand Gulf formation, the 

 Vicksburg group, and the Mansfield group. 



In 1869 the geological survey of Michigan, which had been brought 

 to a close in 1861 by the outbreak of the civil war, was resuscitated 



