240 The American Geologist. October, 1892 
ticlines and synclines of the subterranean sedimentary sequence; and it 
may I believe, be regarded as certain tliat tiie submarine undulations have 
a similar or complementary relationship. We find in the new geology, as 
Hutton found in the old, that geography and geology are one. We find, 
as we suspected, that the physiognomy of the face of our globe is an un- 
erring index of the solid personality beneath. It bears in its lineaments 
the characteristic family features and the common traits of its long line 
of geological ancestors. 
Such, it seems to me, is an imperfect account of the introductory para- 
graphs of that great chapter in the new geology now in course of in- 
terpretation by geologists of the present day; and we have translated 
them exactly in the old way by the aid of the only living geological lan- 
guage, the language of present natural phenomena, and 1 doubt not 
that sooner or later the rest of this great chapter will be read by the 
same simple means. 
I have confined myself to-day to the discussion of the character- 
istics of the simple geological fold as reduced to its most elementary 
terms of arch, trough and unbroken septum; for this being clearly un- 
derstood, the rest naturally follow^s. But this twisted plate is really the 
key which opens the entire treasure-house of the new geology in which 
lie spread around in bewildering confusion facts, problems, and conclu- 
sions enough to keep the young geologist and other scientific men busi- 
ly at work for many a long year to come. 
Into this treasure-house I often wander myself, in the few leisure 
hours that I can steal from a very busy professional life; and out of it I 
bring now and again heresies that sometimes amuse and sometimes hor- 
rify my geological friends. As you have so patiently listened to what I 
have already said, perhaps you will permit me in a few final sentences to 
indicate in brief some of those novelties which I see already more or 
less clearly, and a few of those less novel points on which it appears to 
me that more light is wanted. My excuse is two-fold — first, to furnish 
material for work and controversy to the young geologists; and second, 
to obtain aid for myself from workers in other walks of science. 
The account of the simple rock-fold I have already given you is of 
the most elementary kind. It presupposes merely the yielding to tan- 
gential pressure from front and back, combined with effectual resistance 
to sliding. But in the layers of the earth-crust there is always, in addi- 
tion, a set of tangential pressures theoretically at right angles to this. 
The simple fold becomes ?i folded fold, and the compound septum twists 
not only vertically but laterally. On the surface of the globe this 
double set of longitudinal and transverse waves is ever^^where apparent. 
They account for the detailed disposition of our lands and our waters, 
for our present coastal forms, for the direction, length, and disposition 
of our mountain-ranges, our seas, our plains, and lakes. The compound 
arch becomes a dome, its complementary trough becomes a basin. The 
elevations and depressions, major and minor, are usuallj' twinned, 
like the twins of the mineralogist, the complementary parts being often 
inverted, and turned through 180 (compare Italy with the Po-Adriatic 
