BH d 
eases ARCHEOLOGY IN BRITISH GUIANA 119 
percent. The pattern of change shown by these plain wares makes 
it possible to divide the Mabaruma Phase sequence into three distinct 
parts: an early period with Mabaruma Plain dominant, a middle 
period with Hotokwai Plain very abundant, and a late period with 
Koberimo Plain and Hosororo Plain in the majority. This situation 
makes it easy to identify the general chronological position of any 
unselected surface collection. 
Decorated sherds comprise 13.8 percent of the total pottery from 
Mabaruma Phase sites. These were classified into four decorated 
types, three of which occur throughout the Phase. Mabaruma In- 
cised, with one to three broad incisions along the top of strongly 
everted rims, is most popular in the early part of the sequence, where 
it reaches a maximum of 4.5 percent. It declines in popularity to 
0.1 percent at the latest site. Aruka Incised shows a steady trend of 
increase from 1.9 percent at the lowest level of N-1 to between 11.7 
and 15 percent in the latter part of the Phase. Two of the design 
motifs are restricted to the middle and upper part of the sequence: 
Motif 3—Zoned, and Motif 4—Lines on the interior of everted rims 
(fig. 48). Akawabi Incised and Modeled, in which modeling is com- 
bined with incised designs, shows a similar increase from 1.2 percent 
to a maximum of 11.7 percent, but declines slightly toward the end 
of the Phase. Three of the motifs of this type are time markers: 
Motif 83—Barrancoid adornos, characteristic of the early and middle 
part of the sequence, is replaced by Motif 4—Non-Barrancoid ador- 
nos and Motif 5—Conical nubbins in the later sites. The fourth 
decorated type, Kaituma Incised and Punctate, is restricted with the 
exception of three sherds to the latter half of the sequence, where it 
fluctuates between 0.7 and 4.9 percent without showing any directional 
trend. The various unclassified decorated sherds are too few and too 
sporadic in occurrence to be of value as time markers. 
Trends in vessel shape popularity are difficult to detect because of 
the small rim sample per level. Furthermore, any apparent tem- 
poral difference in vessel shapes between pottery types is more likely 
to reflect the differential frequency of the types than a real difference 
in the popularity of the vessel form. Koberimo Plain, for example, 
produces only late shapes because it is a late pottery type. To elimi- 
nate such extraneous factors, similar forms in the various pottery 
types were combined and the totals tabulated by levels in seriated 
order. The results indicated that most of the plain ware vessel shapes 
were made throughout the Phase, a popular form being transferred to a 
new ware as an earlier one died out. 
Since all of the decorated types occur throughout the Phase with 
very minor changes in frequency, with the exception of Kaituma 
Incised and Punctate, the vessel shapes were analyzed by presence or 
