394 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1954 



Table 1. — Terrace elevations on the Euphrates and tributaries of the Tigris 



These terraces presumably result from climatic fluctuations in the 

 Pleistocene period. As Hitchin notes, the coarser material contained 

 in terrace gravels may be evidence of past pluvial periods. Wright 

 (1952, p. 18) indicates that on the "basis of climatological and physi- 

 ographical reasoning," deposition may be correlated with either dry 

 or wet climate. In apparent support of Hitchin's suggestion, Wright 

 (ibid.) finds correlation of deposition with relatively humid or wet 

 phases in northeastern Iraq. The nonconformity of several of the 

 readings on the Tigris Eiver drainage may indicate local tectonic 

 movements. With regard to the latter possibility, Lees and Falcon 

 (1952, p. 27) state that in the Mesopotamian region (at least in the 

 southeastern area) the history of recent movements of the mountain 

 zone is shown by terraces in the river valleys leading from the plains 

 into the mountains. The elevation of the mountains was not uniform 

 but episodic. 



Thus we appear to have two solutions for the formation of the 

 river terraces within the confines of Iraq. In upper Iraq we find ter- 

 races reflecting climatic fluctuations — terraces which must have also 

 been dependent upon episodic elevation movements of the Zagros 

 Mountains. The problem of which factor, climatic fluctuation or tec- 

 tonic movement, played the dominant role in the formation of the 

 terraces in northern and northeastern Iraq, may be a hard one to solve. 

 That the future holds promise for the establishment of a geological- 

 archeological chronology for the Zagros-Mesopotamian belt is revealed 

 by Wright (1952, p. 24), who states that the relation of the moun- 

 tain streams to the historical development of the Mesopotamian plain 

 is "susceptible of solution" in a fairly detailed chronological system. 



In my own reconnaissance of the Zagros mountain chain in the gen- 

 eral area of northern Iraq no evidences of glaciation were seen. This 



