736 é WILLIAM F. JONES 
Thomonde anticline, which becomes broad and symmetrical, in the 
middle and forms the dominant feature of the structure. Along 
the north flank of the central range the contact between this series 
and the underlying limestone is probably a fault. 
The northern part of this plain is very flat and grass-covered. 
Going south there is a progressive increase in the erosional dissec- 
tions and excellent sections are exposed in the several large streams 
north and west of Maissade. East of Hinche along the RiverSamana, 
on the road from Hinche to Las Cahobes, and in the southerly por- 
tion of the plain in general well-exposed sections are numerous. 
Fic. 4.—Las Cahobes beds rising above level of the plain, east of Las Cahobes 
Limestone fragments have not been noted as entering into the 
make-up of the beds. The material is derived almost entirely from 
the old Paleozoic series and the igneous rocks associated with it. 
Divisions.—In Haiti for the purpose of facilitating structural 
delineation the writer divided this series of sediments into three 
divisions, purely on a lithologic basis. The distinction holds wher- 
ever the series is exposed. 
1. Lower—Thomonde Beds 
The lowest division, called the Thomonde beds, consists almost 
entirely of fine-grained sediments, chiefly fine, bluish, soft shales. 
The thickness of this member varies and it seems to be thinner 
along the eastern side of the central plain. Its maximum thickness 
17) moe § 
