144 BUREAU OF AMERICAN ETHNOLOGY [Bull. 177 
All of the Koriabo Phase sites produced a considerable number of 
sherds of Mabaruma Phase origin. Of the total sherds from the 
Phase, 8.6 percent represent Mabaruma Phase plain wares and 4.8 
percent represent Mabaruma Phase decorated types. In addition to 
Hosororo Plain, Hotokwai Plain, and Koberimo Plain, there are 
probably some sherds of Mabaruma Plain that were missed in classi- 
fication. Mabaruma Plain is so similar in paste characteristics to 
the wares of the Koriabo Phase that it was impossible to separate the 
eroded sherds with certainty. All of these types have a somewhat 
erratic frequency, as might be expected from their origin. Trade on 
an individual basis would result in unequal distribution of the vessels 
among members of the village through time, which the small size of 
the strata cuts tends to bring out. Nevertheless, it is evident that 
Koberimo Plain is the most abundant plain ware, followed by 
Hosororo Plain, with Hotokwai Plain the least common. 
All four of the Mabaruma Phase decorated types occur in Koriabo 
Phase sites. Mabaruma Incised is by far the least common. Kaituma 
Incised and Punctate is most abundant in the first half of the sequence, 
thereafter being represented by only scattered sherds. Aruka Incised 
and Akawabi Incised and Modeled appear to have been popular 
throughout the Koriabo Phase (fig. 57). Analysis by design motifs 
shows that all five motifs of Aruka Incised are present; Motifs 1, 2, 
and 4 of Akawabi Incised and Modeled; and all motifs of Kaituma 
Incised and Punctate. 
DIAGNOSTIC FEATURES OF THE KORIABO PHASE 
The description of the Koriabo Phase is based on pottery changes 
in six strata cuts placed in four different habitation sites. The vil- 
lages range in size from 1,800 to 7,400 square meters with the refuse 
deposit never exceeding 82 cm. in depth and usually considerably 
less. They are located on riverbanks above the flood level, near 
regions where there is sufficient land for slash and burn agriculture, 
although old clearings could not be correlated with the archeological 
sites. 
Koriabo Phase pottery was classified into three plain wares and 
two decorated types. The two major plain pottery types, both sand 
tempered, are an orange-cored Koriabo Plain, which increases in 
popularity throughout the sequence, and gray-cored Warapoco Plain, 
which declines in frequency. A minority plain type, Barima Plain, 
tempered with cariapé, grows in popularity from 1.2 percent to a 
maximum of 6.8 percent in the middle of the Phase, and then declines 
again to 1.1 percent. The two decorated types are distinctive. 
Koriabo Incised is characterized by sharp, carefully executed, 
V-shaped incisions, sometimes combined with low applique ridges, 
