BIG SPRING PRAIRIE. 87 



examination of numerous specimens proved that none 

 of them were conifers The species could not be defi- 

 nitely determined, but there is no doubt that several 

 species occurred. The species most probably were 

 cottonwoods, elms, ash, and willows. Even if the ex- 

 act species can not be definitely determined, the fact 

 remains that a forest formerly flourished on a rather 

 large area, where within the memory of man, only a 

 typical semi-marsh existed. It is also an indisputable 

 fact that this forest was destroyed from some cause, 

 and preserved in an accumulation of plant remains. 

 Since the cause is practically unknown, it may be in 

 order to offer a possible and probable theory in regard 

 to the matter, especially as some further data concern- 

 ing the depth and nature of the various soil strata 

 have been secured since writing the portion relating to 

 that subject. While drilling a well on the Phelps 

 Celery Farm just south of the Brown Ditch, the follow- 

 ing strata were encountered and depths of each were 

 learned: 



Muck 6 ft. 



Clay shading into marl 3 ft, 



Marl, quicksand and gravel 9 ft. 



Total 18 ft. 



The gravel rests directly upon the rock strata, 

 which are here 18 feet below the surface. About 40 rods 

 or so north of this well, the strata were found to be of 

 the following depths: 



Muck 8 ft. 



Clay shading to marl 3 it. 



Marl, quicksand and gravel 9 ft. 



Total 20 ft. 



As the surface slopes from the latter well toward 

 the former, the rock strata are nearly horizontal. 



This arrangement and nature of strata proves con- 



