76 BIG SPRING PRAIRIE. 



WOODS ON CLAY BANKS AND CLAY ISLANDS. 



These two divisions may be considered together, 

 as the same factors of shallow muck and a clay subsoil 

 are common to both. By even a slight drainage the 

 water will move down the clay incline, giving the 

 proper condition for the development of thickets fol- 

 lowed by forests upon it. Mr. Peter Brayton stated 

 that a thicket originated in the vicinity of new road 

 No. 2 after the first ditch was dug. The clay subsoil 

 continues the slope of the adjoining ridge. In conse- 

 quence, there was developed a thicket extending from 

 a point southwest of the Big Spring in a westerly and 

 southwesterly direction. In 1895 it was far more ex- 

 tensive than is figured on Map I, for by 1899, many 

 acres had been cleared and brought under cultivation. 



One of the first trees to make its appearance upon 

 these areas is Populus deltoides (Cottonwood), suc- 

 ceeded by Ulmus (Elm), Acer (Maple), and Fraxinus 

 (Ash). The trees in woods just south of new road 

 No. 2 were from 10 to 15 inches in diameter. 



Fig. 16 represents Clay Island of Map II. This area 

 in 1899 contained four elms over 3 feet in diameter, and 

 two over 2 feet in diameter, besides a few smaller ones. 

 There were also about 50 small ash trees, some of which 

 originated from the stumps of former larger trees, as 

 sometimes from four to six of these trees are grown 

 together at the base. All of these trees exhibited the 

 characteristic prominent roots. Some of the clay 

 islands were wooded before the first ditches were dug. 

 The effect of ditching was to cause a more rapid en- 

 croachment of forest upon the surrounding portions 

 which were underlain by a properly sloping clay- 

 subsoil. By 1886, the forest had encroached consider- 

 ably upon the prairie to the southwest, south and south- 

 east of it where the proper natural slope of clay subsoil 

 occurred. In this year a severe prairie fire destroyed 



