July 17, 1896.] 



SCIENCE. 



m 



Potsdam, as a consequence of differential 

 erosion, rise the ranges of the Baraboo 

 bluffs, which also are probably monadnocks 

 reaching a considerable height above the 

 baseleveled plain of central Wisconsin. As 

 to the extent of territory over which this 

 central Wisconsin plain may be traced, I 

 can say nothing, but I anticipate that the 

 area will be found to be large. 



While accurate measurements were not 

 made, the plain in the crystalline rocks 

 apparently has a southern slope. From 

 numerous aneroid measurements from the 

 railroad, near Wausau, by Messrs. Buckley 

 and Weidman, the dissected plateau both 

 east and west of the Wisconsin River rises at 

 many places to a uniform elevation of about 

 1,400 feet. At the Wausau bridge the river 

 is about 1,180 feet above the level of the sea. 

 In order to reach the baseleveled plain, one 

 must therefore climb to a height of about 320 

 feet above the river. At Mosinee the river is 

 about 1,100 feet above the level of the sea, 

 and here the plain is estimated to be 200 

 feet above the river level. This gives a 

 southern slope to this plain between Wau- 

 sau and Mosinee, a distance north and 

 south of about 12 miles, amounting to at 

 least 100 feet. 



On the geological map of Wisconsin* it 

 will be seen that the Paleozoic formations 

 about the pre-Cambrian core of central Wis- 

 consin constitute a very gently southward 

 plunging anticline. How far erosion had 

 gone toward a baselevel in the crystalline 

 area before Cambrian time is undetermined, 

 but the uniform fashion in which the streams 

 cut the Potsdam and strike the crystallines 

 at about the same level for considerable dis- 

 tances away from the main Archean area 

 indicates that if not baseleveled at the time 

 of the Cambrian transgression, the area ap- 

 proached a peneplain. 



As to the age of the central Wisconsin 

 baseleveling no more than conjectures can at 



* L. c, PI. I. 



present be given. One naturally connects 

 it with the Cretaceous transgression, which 

 extended very far over the Upper Missis- 

 sippi valley, and perhaps over all of it. 



As to the agent or agents which accom- 

 plished the baseleveling, no evidence was 

 obtained, but because calculations show 

 that running water is far more potent as a 

 denuding agent than the ocean, I incline to 

 the belief that the major part of the work 

 was done by rivers, although it is possible 

 that as a result of the transgression of the 

 ocean some of the final work may have 

 been that of marine denudation. 



Observations upon which the above arti- 

 cle is based were made by me while on a 

 trip with some of the advanced students of 

 the University of Wisconsin, the primary 

 purpose of the trip being to study the crys- 

 talline formations of central Wisconsin. It 

 is hoped at a future time to take accurate 

 measurements of the heights of the river 

 terraces and of the baselevel at various 

 points, in order to give a more exact ac- 

 count of them. 



C. E. Van Hisb. 



DECIMAL NUMERATION IN THE UNITED 



STATES. 



Mr. Herbert Spencer's arguments 

 against the adoption of the metric system, 

 republished in the June number of Ap- 

 pletoji's Popular Science Monthly, are chiefly 

 based upon the idea that the division of 

 measures into tenths is so inconvenient that 

 men ' under the pressure of business needs ' 

 tend to abandon the decimal system in favor 

 of the duodecimal. Whatever may be the 

 case in England, it is evident that in the 

 United States the tendency is quite the op- 

 posite, and that we are gradually bringing 

 the divisions of our weights and measures 

 into accord with our notation. This evo- 

 lution is not being accomplished by ' Bu- 

 reaucratic Coercion,' but by the free action of 

 natural forces, the beneficient results of 



