408 GEOLOGY OF NORTHWESTERN TEXAS. 



About one mile above the confluence of the Salt Croton Creek with the 

 Salt Fork of the Brazos are the falls of Croton Creek. The water has a fall 

 of about six feet. At the time of our visit there was as much water in Cro- 

 ton Creek as there was in the Salt Fork of the Brazos, and it is said to run 

 about the same amount the entire year. 



The following section was made at the falls: 



section no. 19. 



1. Blue clay 4 feet. 



2. Limestone in layers, fossiliferous 8 feet. 



3. Massive white gypsum 30 feet. 



Total 42 feet. 



The fossils recognized were two species of Ammonite, Orthoceras, and Pleuro- 

 phorus. The upper part of No. 2 of the above section was almost entirely 

 composed of Ammonites? 



Three miles above this place is Salt Flat, a place where the water at times 

 spreads out over a broad flat, which on evaporation leaves a heavy incrusta- 

 tion of salt. The water comes from a spring that breaks up through a spotted 

 clay. The flat embraces about two hundred acres in area. 



section no. 20. 



Made at Salt Flat. 



1. Spotted red clay 3 feet. 



2. White massive gypsum 10 feet. 



3. Red clay 30 feet. 



4. Gypsum 1 foot. 



5. Red clay 30 feet. 



6. Gypsum 6 feet. 



7. Red clay 20 feet. 



8. Limestone 1 foot. 



Total Ill feet. 



All the lateral streams flowing into Croton Creek for several miles are very 

 salty. The hills are high and are composed of gypsiferous red sandy clays, 

 and disintegrate rapidly. From Dove Creek to the top of the hill one mile 

 north there is a difference of two hundred and sixty feet by barometric 

 measurement. 



