Marcu 21, 1907] 
NATURE 
rough sketch accompanying our former report, which shows 
how the Bujuku derives its supplies from a much larger 
part of the snowy area than does the stream hitherto con- 
sidered to be the upper course of the Mobuku. The Duie 
was not able to define so clearly the drainage on the side of 
the Semliki, but he says that the streams flowing west from 
the four main passes leading in that direction all unite to 
form the Butagu, the valley of which has been the usual | 
In the Ice age | 
line of approach to the snows on this side. 
the whole of the valleys of the Bujuku, Mobuku, and 
Mahoma (south of, and parallel to, the Mobuku) were 
filled with glaciers of the first order, which must have 
united and descended the Mobuku valley for some distance. | 
Similarly, glaciers descending from the three southern- 
most of the groups must have united to form a great west-| 
ward-flowing ice-stream. At present the lowest 
reached by a glacier (that which feeds the 
Mobuku) is 13,682 feet. The permanent 
snows are included in a circle ten miles in 
diameter. » 
It should be mentioned that the Royal Geo- 
graphical Society proposes to apply the Duke’s 
name to the most southerly of the snowy 
massifs, instead of that of Thomson, who 
himself never saw Ruwenzori, important as 
his work was for the general opening up of 
this part of East Africa. 
MAN AND SUPERMAN. 
ME. -ARTHUR J. DAVIS, of the U.S. 
Reclamation Service, describes in the 
National Geographic Magazine for January 
the startling changes that are now taking 
place in the region north of the Gulf of Cali- 
fornia. For 150 miles from the apex of the 
gulf, an area of delta and aliuvium and old 
sea-bottom extends to the north-west between 
the mountains. The upper part of this basin 
forms the Imperial Valley, and lies in the 
territory of the United States. Below the 
Mexican frontier, the Colorado River, emerg- 
ing from the hills, has built up a huge alluvial 
barrier above the level of the land to the 
north of it. This in its growth cut off the 
head of the ancient gulf, and led to the 
gradual disappearance of the water by evapor- 
ation. 
The Imperial Valley thus came into exist- 
ence, with part of its floor 300 feet below the 
level of the adjacent sea, and a variable lake 
without an outlet, the Salton Sink, at its 
northern end. From time to time the 
Colorado River, in seasons of flood, has 
diverted itself from the elevated delta into the 
Salton Sink, and the lake has grown in con- 
sequence. At other times it has banked itself 
out of this region, has flowed again into the 
Gulf of California, and has left its temporary 
northward-running channels, the Alamo and 
New Rivers, practically dry and sand-filled. 
The ease with which the northern lowland 
could be irrigated led to the formation of a 
canal about seven years ago. Its mouth, how- 
ever, became silted up, and a spot was 
then selected above a steeper slope, where 
the velocity of the water leaving the 
Colorado was greater and more effec- 
tive. In May, 1905, however, the first serious flood-waters 
deepened this new channel, and supplied far more water 
northward than was required. The ‘‘ Salton Sea’’ rose 
rapidly, and the Southern Pacific Railroad along its 
margin was equally rapidly moved to higher ground. 
Striking alterations occurred in the old valley-floors as 
they were invaded, and the cataract of the New River, 
cutting its way back to the frontier town of Calexico, 
flowed there in a channel 45 feet below the level of the 
NO. 1951, VOL. 75 | 
| 
farm-lands. The peril became so great in 1906 that a 
huge dam was constructed on the delta, in order to compel 
the Colorado River to return to its former route into the 
Gulf of California. Mr. Davis’s account of this titanic 
struggle—the printer makes him speak of ** herculanean 
efforts ’—forms very interesting reading. The dam having 
been completed last November, it was estimated that the 
enlarged *‘ Salton Sea’’ would dry up in about twelve 
years; but in December the water of the Colorado worked 
its way round the dam, and resumed its rush into the 
Imperial Valley. 
The great cataract in the New River was in January eat- 
ing its way backward, that is to say southward, at the rate 
of a mile in three days, with a width of some 1700 yards 
and a fall of 100 feet. The farms in the Imperial Valley 
point | are unable to avail themselves of the water so copiously 
Upper figure.—Partial destruction of the town of Mexicala, Mexico, by the New River. 
Lower figure.—Vhe New River cutting into the farm-lands near Imperial, California, 
forming banks 70 feet in height, which are constantly falling in. 
supplied, since it lies below their level; a great inland sea is 
arising, and dispossessing the railroad and the people 
whom it serves ; and the probability of the diversion of the 
whole Colorado River northward threatens to deprive of 
water the settlers in Arizona and Mexico from the Grand 
Canon down to the Gulf of California. It needs the 
philosophic spirit of a Lyell to regard physiographic 
changes. of such magnitude with admiration rather than 
dismay. 
