E d 
eens a ARCHEOLOGY IN BRITISH GUIANA 241 
TaBLeE K.—Duration of the Taruma Phase calculated on the basis of a 10-percent 
change in frequency of Yoché Plain 
Interval Duration 
21 
From E-17, Cut ie 8-16 em. to E-9, ‘Cut I; 8-16 cm., iipluai welt ess. Resear aes Tee 25; 
From E-7, ‘Cut 1, 0-18 cm. to E- 16, Cut 2; 0-8 cm., dniclushveecs Ctlase ee ee ae 32 
From E- 10, Cut i, 8-16 cm. to E- 22, Test A, inclusive Pee te ee en eee 5 Ste Bree eee SESE 18 
From E-18, Tests to E- 24, Cut 1 , 8-16 cm., inaititeve nce wee Ree TN Sta ee 19. 
From E-30, Cut 1, 16-24 cm. to E- IS NCat) 10-8femtsinclusivess et Pe i es 16. 
From E-10, Cut 1, 16-24 em. to E-1, Cut 1, 8-16 cm., intuisiverst. soe eet ON et 10. 
From E-4, Test to E- 1, Cut 1, 16-24 cm., jachusivet med ots s0icecumibis puminp sige ate 13 
From E-1, Cut 1, 24-32 cm. to E-6, Cut , G24) CIs ANCIUSIVO= 222 oo eee ee BE 16.4 
From E-30, Cut i, 24-32 cm. to E-9, Cut 2, 0-8 cm., qnolisives.2 4204. oh Bee ea Te 17.6 
From E-5, ‘Cut 1, 8-16 em. to E- 14, Tests, Mnclusivest2 tc ne a ee ee ee 10.5 
hoOsalCurawOl Ol balun, Ease sen cock ae ake Lew ean eae ee eee oe ee 204.4 
Since the agreement between the historically reported duration and 
that derived from refuse accumulation calculations described above is 
reasonably good, the experiment was continued with the new factor 
injected here, namely, rate of pottery change. The total amount of 
pottery change during the Taruma Phase seriated sequence (fig. 101) 
is between 63 and 64 percent. Yochdé Plain declines from 96 percent 
to 32 percent, a change of 64 percent. At the same time, Kalunye 
Plain increases from 3 percent to 66 percent, a change of 63 percent. 
If 63.5 percent is taken as the average amount of change and 207 
years the average duration indicated by the amount of refuse accumu- 
lation, then the rate of pottery change is 1 percent per 3.26 years in 
the Taruma Phase. This rate can be compared with the Rupununi 
Phase, where both archeological seriation and historical data are also 
available, but where the refuse density formula could not be used. 
The Rupununi Phase is estimated from historical evidence to have 
existed in British Guiana for about 200 years (see pp. 326-332). Dur- 
ing the seriated sequence (fig. 125), Rupununi Plain increases from 11 
percent to 79 percent, a change of 68 percent, while Kanuku Plain 
declines from 88 percent to 21 percent, an alteration of 67 percent. 
At a rate of 1 percent per 3.26 years, these changes in pottery type 
frequency correspond to 221.6 and 218.4 years respectively, and agree 
closely with the historically known duration, suggesting a rate of pot- 
tery change very similar to that in the Taruma Phase. 
To test further the universality of this rate of pottery change, the 
Abary Phase can be used. This Phase was estimated from the rate 
of refuse accumulation formula to last either 298 or 417 years, de- 
pending on which cuts were used to arrive at the total duration (see 
pp. 179-182 for details). Tiger Island Plain shows a change in fre- 
quency of 84 percent, declining from a maximum of 88 percent to a 
minimum of 4 percent, which at the rate 1 percent per 3.26 years gives 
273.8 years. ‘Taurakuli Plain shows a 95-percent change in frequency, 
increasing from 19 percent to a peak of 94 percent and then declining 
