Origin stories collected among the indigenous peoples in the Windward Islands during the early colonial period have been interpreted as indicating a mainland Carib affiliation for the islanders. This interpretation gave rise to efforts in the present century to identify the archaeological correlate of the presumed late prehistoric or protohistoric migration of Cariban speakers into the Lesser Antilles. Recent debate centers around two models. One of these associates the supposed migration of mainland Caribs into the Lesser Antilles with the advent of the Suazey ceramic complex in the twelfth century; the other implies either a protohistoric migration or an episode of rapid acculturation of island populations to South American mainland Carib culture in the fifteenth or sixteenth centuries. A review of relevant archaeological, historical, and linguistic evidence provides little support for either of these models. Instead, the so-called “Island Caribs” were Arawakan speakers, probably longtime residents of the Windward Islands whose cultural and linguistic connections with the mainland Caribs probably were the products of contacts related to trade and alliance.

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SECURITY CLASSIFICATION AUThIORIT'r 3 :iSTRIBUTION/AVALA8LITY OF REPORT DECLASSiFICATION I DOWNGRADING ,C'EDULE PERFORMING ORGANIZA.TION REPORT NUMBER(S) 5. MONITORING ORGANIZATION REPORT NUMBER(S) COELMN/PD-88/06 ,A. NAME OF PERFORMING ORGANIZATiON 16. OFQICE SYMBOL 7a. NAME OF MONITORING ORGANIZAION ' UNCLASSIFIE D/U NLI MITE D M SAME AS, RPT, 0 DTIC USERS •NAME OF RESPONSIBLE INDIVIDUAL i22o ;EPE.HONE (Include Area Code) I 22c. OFFICE SYMBOL) Form 1473, JUN 86 Prevous editions are obsolete. SECURIT v CLASSIFICATON OF THIS PAIGE Ii 18.

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A microbit apparatus has been used to study how and why field drilling rates are usually higher when air is circulated rather than liquids. Our laboratory results with air are compared with the work of others who have circulated liquids to remove cuttings, and a theory for air drilling has been developed.Chief results of this program are that most of the parameters operative in liquid drilling are also operative in air drilling, but in air drilling many of these factors are much less detrimental to the drilling rate. Our major conclusions are that drilling rates with air are much greater than with liquids because chip removal is facilitated by: (a) low bottom-hole pressure exerted by the column of air, (b) low viscosity of air which permits it to enter cracks more readily, (c) less restriction to widening crack by highly compressible air, and (d) low cohesive forces between rock particles in environment of air. Furthermore, there is far less plugging of widening cracks around chips because of the absence of solids from the drilling fluid and the better hole cleaning afforded by the high-velocity air stream. The greatest reason for high drilling rates with air is that the air is greatly cooled by expansion as it passes through the bit and thereby cools the bottom of the hole to reduce the stresses exerted on the rock by the overburden. Overburden pressure, liquid saturation of the rock and rock ductility have a more adverse effect on gas drilling than drilling with liquids. The effect of overburden pressure is greatest on dry rocks. The data presented suggest: (a) the use of gases to drill with where possible, (b) the use of clear liquids rather than mud where possible, (c) the use of th8 highest filtrate muds possible where mud is required, (d) the use of liquids having the greatest ability to wet the formation, where liquids are. required, and (e) placing fluid ports of bit such that greatest cleaning action of hole bottom can be achieved. The largest practical volumes of air should be circulated to increase velocity and pressure drop at the bottom of the hole and thereby provide better cleaning and greater cooling of the rock being drilled. of, References are listed on page 17.