220 The American Geologist. Aprji, isd!' 
finished peneplain, ratlier strongly dissected, with deep soils 
overlying- the uplands ot gneiss and schist. Stone mountain, 
a superb monadnock of abrupt form, consists of fine homoge- 
neous granite, quite unlike the rocks of the peneplain ( Puring- 
ton. Amer. (ieol., xiv, 1894,105-108). Van Hise, in describ- 
ing tlie uplands of the ancient disordered and indurated rocks 
in north-central Wisconsin, says that they constitute "as near- 
ly perfect a baselevel plain as it has been my good fortune 
to see. * * * Above the valley of the Wisconsin river, 
an almost perfect plain is seen * * * large areas of 
which are but little dissected by any of the tributary streams 
of the Wisconsin." The upland j^lain is surmounted by Big 
Rib hill, a monadnock of exceedingly resistant quartzyte (Sci- 
ence, N. S., iv, 1896, 57-59). The upland of the Slate moun- 
tains in western Germany is a wonderfully fine peneplain of 
broad and gentle undulations, now undergoing active dissec- 
tion by the branches of the Rhine, Mosel. and other stronc 
rivers which have eroded their steep-sided valleys deep be- 
neath its even surface. The upland is surmounted by several 
ridges or elongated monadnocks; and some of these at least 
are composed of a very resistant quartzyte. In Xew England, 
the type Monadnock is, if my memory serves me, largely com- 
posed of an andalusite schist, wdiich certainly has every appear- 
ance of being a resistant rock. Yet it must be freely admitted that, 
as far as I know, no artificial test has been made of its re-' 
sistance as compared with that of many apparently resistant 
rocks around its base. It may be added that an appropriate 
test would be difficult to devise, inasmuch as exposure for 
ages to the weather would certainly be the best means of dis- 
covering the way in which long ages of weathering will afifect 
a rock. In view of this dif^culty, I hope that those wdio regard 
the peneplain explanation as compulsory will not be left alone 
to devise appropriate tests to determine the resistance of mon- 
adnock rocks, but that Professor Tarr and any others who 
are interested in the development of land forms, but who feel 
no such compulsion from the peneplain theory, will neverthe- 
less turn their ingenuity in this direction. It is the truth of 
the matter that we are all striving for, not the maintenance of 
this theory or that; and it seems unfriendly if not unscientific 
to say that "the burden of proof should rest with the advo- 
