32 SURFACE GEOLOGY. 



several agencies — icebergs, glaciers, landslips, and waves of translation — which, 

 indeed, operated most powerfully in the earliest periods, but have ever since con- 

 tinued to act and are still acting. And so of alluvial agencies : we find evidence 

 of their operation from the close of the tertiary period; nay, much further back; 

 but they have gone on increasing in power to this time. Thus the drift and allu- 

 vial agencies have had a parallel operation from the first, and hence the difficulty 

 of separating drift and alluvium, and the propriety of regarding the whole as one 

 prolonged period, with synchronous deposits. These views will be more fully 

 developed in the subsequent parts of this paper, and I mention them now to avoid 

 misapprehension. 



In Professor Owen's Report on the Geology of Wisconsin, Iowa, &c, many inte- 

 resting facts in surface geology are mentioned; such as terraces and old river beds. 

 On the St. Peter's river he describes two terraces above the meadows, one 130 feet, 

 and the other 230 feet high — the latter of coarse materials. On Red river, 

 according to Captain Marcy [Report, p. 35), are three, the lowest from 2 to 6 feet 

 above the stream; the second from 10 to 20 feet; and the third, from 50 to 100 

 feet; forming the most elevated bluffs along the river. 



On the River Jordan, in Palestine. Dr. Anderson, geologist to the exploring 

 expedition sent out by the United States Government to the Dead Sea, has given 

 us an account of the terraces in the valley of the Jordan, a river so remarkable 

 for its tortuosities and rapid descent. He says : " There are almost everywhere in 

 the Jordan valley, distinct traces of two independent terraces. The upper terrace 

 extends to the basis of the rocky barriers of the Ghor, both on the east side and 

 the west, and appears to have been due to a geological condition long preceding 

 the existence of the actual river, yet subsequent to the removal of the material 

 which once occupied the space between the two opposing cliffs." We understand 

 him to mean that there are two terraces besides the meadows, or lower bank of the 

 river; so that I should speak of the river, according to the views presented in this 

 paper, as having three terraces. Near Beisan, or Scythopolis, Dr. Anderson says 

 there are three terraces — four I suppose by my nomenclature. He does not make 

 an estimate of the height of the two great terraces of the Jordan, though in one 

 place he speaks of banks of stratified gravel rising sometimes 100 feet. Dr. Robin- 

 son, in his Biblical Researches in Palestine, &c, describes the valley of the Jordan 

 near the Dead Sea, and says that the immediate valley, which is usually nearly a 

 mile wide, is bounded by a terrace (the first or lowest of Dr. Anderson I suppose) 

 50 to 60 feet high at its southern part, but not more than 40 feet further north. 

 He also describes a small terrace near the Dead Sea, only 5 or 6 feet above the 

 meadow, which does not extend far up the stream. The width of the whole ghor 

 or valley to its rocky sides varies from 5 to 10 or 12 miles. 



Delta and Moraine Terraces. 



Very distinct delta terraces may be seen near the mouths of most of the tributa- 

 ries of the Connecticut and on the branches of those tributaries; but they do not 

 occur usually at the present mouths of the streams, but rather at the point where 



