8 



1st. Recent. A surface layer of a few inches to a foot or more 

 in thickness composed of a rather coarse gray, sandy loam, known 

 as the Columbia sands. 



2nd. Pliocene? Lafayette Formation. About 20 or 25 

 feet of variegated clays and sands, often highly and attractively 

 colored. These may be seen at the big water cut across Home 

 Avenue above Mr. McNair's place. 



3rd. Middle Fresh Water Cretaceous : Magothy Formation : 

 Drab or black clays only a few feet in thickness, containing much 

 lignite and vegetable matter. Many pieces of wood occur in this 

 stratum, perfect in shape but very soft. 



4th. Lower Fresh Water Cretaceous: Potomac Formation. 

 This is the oldest of the coastal plain deposits, resting uncon- 

 formably on the crystalline, igneous rocks below. It is character- 

 ized by absence of fossils, distinct banding, and the thickness of 

 its component layers of sands, clays, arkoses, gravels, etc. It is 

 often stained with iron or other pigments, and mica is plentiful. 

 It is from the sands of this formation that the artesian water that 

 supplies the town is obtained. This water is as nearly pure as 

 ground water can be, and its remarkable clearness and sparkle 

 make it unsurpassed as a table water. 



In the lower part of the county there is unterpolated between 

 the Lafayette and the Magothy a deposit of Miocene marls of 

 marine origin, and at places there are outcrops of this formation 

 that have been worked for agricultural lime. 



The general surface configuration of the country south of Black 

 Creek valley is that of a remarkably level plain, with gentle eleva- 

 tions and depressions, and occasional erosion cuts by the streams. 

 As a result of this topography the surface drainage is often not 

 good and open ditches are much used to empty pockets and lower 

 the water surface in cultivated land. Except on a very few sandy 

 knolls on the southern rim of the creek valley, that are really 

 outposts of the sand hills, the nature of the vegetation on the level 

 plain is determined very largely by the position of the water 

 surface in the soil, and it is easily seen that the main ecological 

 plant formations are dependent chiefly on this factor. 



According to the United States Soil Survey of Darlington 

 County there are in the immediate neighborhood of Hartsville 

 five types of soils. The town itself is shown in their map as 

 situated on the Orangeburg sandy loam, but there is evidently 

 some mistake here* as this type is described in the text as con- 



*The town really stands, I think, on the Norfolk sandy soil and the Golds- 

 boro compact sandy loam. 



