. 144 THE COASTAL PLAIN, OF NORTH CAROLINA.

  
   
   
    
   
   
   
 
   
 
 
    
  
   
  
  
 
  

Of the 35 or more determinable species enumerated in the above list,
at least 25 are identical with species present at the Snow Hill locality.
The evidence seems to be reasonably conclusive that the Snow Hill and
Blue Banks Landing horizons are approximately synchronous.

About one-fourth mile below Blue Banks Landing a dark-green clay
which contained a few fossils of the Black Creek formation was ob-
served exposed to a height of 6 feet above water level.

A poor exposure of dark-green sand was observed at Randolph Land-
ing 6 miles above Greenville, and this was the last place at which the
Black Creek beds were seen in descending the river.

South of Cape Fear River there are but few exposures of Black Creek
materials within the limits of the State. The lack of natural exposures
is due to the fact that the stream incisions are shallow, and conse-
quently the valley slopes are gentle and covered with vegetation.

The descriptions given by well owners and drillers of the materials
penetrated in various borings in western Bladen and the southeastern
half of Robeson counties furnish evidence, however, of the widespread
occurrence of the Black Creek formation at shallow depths beneath
the surface in these areas.

The buried coastward extension of the Black Creek formation has i
been recognized in two deep well borings. The first of these is at the
Clarendon Waterworks plant at Wilmington, where the thickness —
amounts to 389 feet, extending from a depth of 720 feet to granite at —
1,109 feet below the surface. The correlation is based upon the occur —
rence of Ostrea cretacea Morton at several horizons between the top and
bottom of the strata indicated (see well section, p. 163). The second well
is at Fort Caswell, near the mouth of Cape Fear River (p. 169), where a
thickness of 400 feet of supposed Black Creek beds makes up the section
from a depth of 1,140 feet to basement rocks at 1,540 feet below the
surface. This correlation is based partly upon the occurrence of Ostrea —
eretacea Morton, which was found at two horizons, namely, 1,200-1,237
feet, and 1,365-1,380 feet, respectively. The strata not included be —
tween these horizons are largely of marine origin, and it seems best t0
tentatively regard them as belonging to the Black Creek formation. _

The equivalency of the Black Creek formation as described by Earle
Sloan in South Carolina with the “Bladen” formation has been proven
by the discovery of the characteristic “Bladen” species Araucaria bla-—
denensis in typical laminated materials at a locality 3 or 4 miles north ©
of Florence, Florence County, a few hundred yards above the mouth of
a small branch of Black Oreck. :