THE LOUISIANA FIELDS ' 70U 



of the main basin, which is defined on the east by tlie Ozark, Arbuckle- 

 Wichita, and Llano-Burnet uplifts, and on the west by the Rocky Moun- 

 tains. 



Louisiana 



location of the field 8 



The main oil and gas district of the Mid-Continent region in Louisiana 

 is just north of Shreveport and is known as the Caddo* field, from its 

 position in and around Caddo Lake. This field has been described by 

 C D. Harris in his report on oil and gas in Louisiana Bulletin Number 

 429 of the United States Geological Survey. It has been more recently 

 covered in detail by George C. Matson in Bulletin Number 619 of the 

 Survey, and to these reports the reader is referred for more complete data 

 regarding details of this district. 



The Crichton or Naborton oil and gas field which lies south of Shreve- 

 port, in De Soto and Red River parishes (counties), is a recent discovery 

 as compared to the Caddo field. It is closely related to the former field, 

 however, in that it occurs on a fold subordinate to the larger Sabine up- 

 lift and produces oil and gas from approximately the same horizons as 

 the former district. 



STRATIGRAPHY 



The main oil horizon in this territory is the Woodbine sand at the base 

 of the Upper Cretaceous or Gulf series. It lies at a depth of 2,300 to 

 2,600 feet. The accompanying general section will show the stratigraphy 

 of the oil region in the north portion of the State and the positions of* the 

 oil and gas sands. 



The general stratigraphic section in oil region of northern Louisiana, 

 in descending order, is as follows : 



Feet 

 Quaternary system. 



Red and gray sand, loam, clay, and gravel 0-50 



Tertiary system (Eocene). 



1. Saint Maurice formation. (Claiborne) Clays, clay-iron con- 



glomerate, and calcareous, glauconitic beds 50-100 



2. Wilcox group. (Sabine) Clays, sands, and conglomerate witli 



beds of dark shale and lignite 400-500 



3. Midway group. Chiefly clays with some limestone 200-300 



( Unconformity. ) 



Upper Cretaceous (Gulf series). 



1. Arkadelphia clay. Dark, stiff clays 300-600 



2. Nacatoch sand. (Gas rock) Shreveport or Caddo gas sand.. 100-130 



3. Marlbrook marl. Blue to dark marl, with chalky layers. Con- 



tains Saratoga chalk member 150-700 



