September 4, 1896.] 



SCIENCE. 



305- 



This publication should stimulate friends 

 of American archaeology to contribute liber- 

 ally to this enterprise, as it abundantly 

 shows that the soil of our own continent 

 offers problems in reference to ancient civili- 

 zation every whit as interesting as those 

 existing in the valley of the ISTile or on the 

 banks of the Euphrates. 



D. G. Brinton. 



Univeesity of Pennsylvania. 



CURRENT NOTES ON PHYSIOGRAPHY. 

 GULF STREAM AND LABRADOR CURRENT. 



Prof. Wm. Libbey, Jr., of Princeton, 

 presented to the Sixth (London) Inter- 

 national Geographical Congress, an ab- 

 stract of the results obtained from serial 

 temperature soundings along the boundary 

 of the Gulf Stream and the Labrador cur- 

 rent, made under his direction by the U. S. 

 Fish Commission southward from the ISTew 

 England coast (Lat. 41° to 39°) between 

 Block Island and Nantucket, in the summer 

 months of 1889 to 1892. Surface and deep 

 currents are separately discussed. The 

 former are found to fluctuate with weather 

 changes ; the most intimate relation ap- 

 pearing between surface winds and the 

 surface termination of isothermal lines 

 (isothermobaths) on vertical north-south 

 sections. The surface currents are continur 

 ally swayed laterally, or hurried or retarded 

 by the winds. Smaller and slower shifts of 

 the deeper currents are found ; while these 

 effects are not yet definitely correlated with 

 their causes, it is believed that they may be 

 the cumulative results of varying sur- 

 face impulses. Twenty-one sections are 

 appended, shaded in red and blue to repre- 

 sent differences of temperature. Unfortu- 

 nately they are without suf&cient indication 

 of place, depth or date. 



PREGLACIAL EROSION CYCLES IN ILLINOIS. 



O. H. Hershey discusses the physio- 

 graphic development of northwestern Illinois 

 on the basis of personal observations, com- 



paring his results with those found by others- 

 elsewhere (Amer. Geol., Aug. 1896). He 

 regards the general upland as a peneplain 

 of Tertiary erosion. It is surmounted by 

 low monadnocks, locally known as 'mounds,' 

 200 feet or more in local relief ; the accor- 

 dant summits of these eminences are ten- 

 tatively taken to indicate an almost 

 destroyed ancient peneplain, probably to be 

 correlated with the peneplain of Cretaceous 

 erosion elsewhere recognized. The uplands 

 are interrupted by broad-floored valleys, 

 and these in turn are trenched by narrow 

 valleys, of late Tertiary and of Quaternary 

 date respectively. The narrow valleys are 

 more or less clogged with drift, concerning 

 which several details are given. The drain- 

 age lines are interpreted as having been 

 modified from ancient consequent courses by 

 continually advancing adjustment to weak 

 structures in successive early cycles ; except 

 that the Mississippi between Iowa and Illi- 

 nois is thought to have first come into ex- 

 istence after the excavation of the broad- 

 floored valleys in late Tertiary time. Taking 

 5 as the time needed for cutting the trenched 

 valleys, 25 is given for the broad-floored 

 valleys, 200 for the uplands, and more than 

 500 for the doubtful ancient peneplain of 

 the monadnock tops ; but all this is admit- 

 tedly very rough. This essay is not only 

 intrinsically valuable for its contents, but 

 interesting as one of the few products of in- 

 dividual work in physiographic exploration- 

 standing in this respect on the same plane 

 with Taylor's studies of the ancient shor© 

 lines of our Great Lakes. 



the piedmont PLATEAU OF VIRGINIA. 



The eighth annual field meeting of the 

 National Geographic Society at Monticello^ 

 Va., was the occasion of an address by Mc- 

 Gee, on the Geographic History of the 

 Piedmont Plateau (Nat. Geogr. Mag., Aug.,^ 

 1896). The undulant and mountain-em- 

 bossed plateau is described as the pene- 



