1876.] Geography and Exploration. 183 
ogists, still widely accepted, the origin of mountains is to be ascribed to 
the elevation of a molten or semi-molten mass which threw up the rocks 
along its axis, and crowded the upper strata to the right and left, forming 
in this way a mountain-chain. But this view is not sustained by observed 
facts, and Suess adopts the modern view of a general horizontal move- 
ment of the mountain system as a whole. The conclusions of Suess 
agree to a very considerable extent with those of Professor Dana in his 
discussion of mountain-making in general. 
In the Alps the exertion of this horizontal force was essentially in- 
fluenced by resistance from four different sources: (1) from the presence 
of foreign masses of older rocks; (2) from the folding mass itself; (3) 
from the occasional introduction of older volcanic rocks, as granite and 
porphyry, in the moving mass ; (4) finally, it appears that single mount- 
ain masses, like the Adamello or the red porphyry, near Botzen, have 
exerted an essential influence on the development of the surrounding 
mountain region. 
If we look at the subject more broadly, however, and pass out of 
Europe to America, and then further study the great mountain-chains of 
Asia, we arrive at this grand conclusion: throughout, mountain-masses 
and mountain-movements are one-sided, and the direction of the move- 
ment isin general northwest, north, or northeast, in North America and 
Europe, but southerly or southeasterly in Central Asia. There is no 
regular geometrical arrangement in mountain-chains. 
In conclusion, it may be remarked that mountain-making as a whole 
can be regarded as a stiffening of the earth’s surface, which process has 
been determined by the distribution of certain older rigid masses. These 
may be made up of mountain lines pushed up together and crossing each 
other, as in Bohemia, or they may consist of widely extended su s 
Whose strata, even the oldest, have retained their horizontal position, as 
n the great Russian plain. These primitive masses conform to no geo- 
metrical law, either in outline or in distribution, though they have deter- 
mined the form and course of the folds which contraction has produced 
in the more pliant portions of the earth’s surface between them. 
GEOGRAPHY AND EXPLORATION. 
EXPLORATION oF THE Upper Mapema Pirate. — Professor James 
n, of Vassar College, is preparing for a third expedition to South 
America, He purposes to explore the unknown parts of the Upper 
Madeira P late, the Rio Beni in particular. This magnificent river, 
the largest tributary to the Madeira, has never been explored ; its course 
= as much a geographical problem as the source of the Nile. The mys- 
terious Madre de Dios is supposed to be an afluent, but it remains to be 
proved. Lieutenant Gibbon was charged by our government to settle 
the question, but he failed in the attempt. Professor Orton intends to 
examine this river mainly in the interest of geographical science ; but 
