Arizona republican., 1910-02-15

lifted such surfaces into colder at
 mosphere, and the creation of new
 mountain ranges and new valleys has provided new avenues for air cur rents with undoubtedly an attendant
 influence upon rainfall. Most prob
 ably, however the chief agency in changing the climate of the earth has been the shifting of the earths axis i from time to time-the tilting' of the poles shifted the Arctic region,
 for example, from direct rays of the
 sun to slanting rays. Hence. where
 once was a warm climate, dense veg citation and swarming animal life. { is now a desert of ice or frozen,
 barren land
 | So much was accepted by science i as a reasonable theory long before , Professor Moore entered the lists IL | is with his theories of forests and t. floods that we are presently con
 cerned We find him saying on page
 Is of his pamphlet:
 But until recent years I did be- lieve that deforestation had an i'm 1 portant and beneficial [sicl effect
 on the conservation; that is on the economical use of the rainfall, and 1 that forests restricted the runoff. But i study and investigation have caused i me to modify my views"
 Further on he says, in italics:
 On the whole. it is probable that | forests have little to do with the
 height of floods in main tributaries
 and principal streams, since they oc- cur only as the result of extensive
 and heavy rains. after the ground is | everywhere saturated, or when heavy warm rains come on the top of deep
 snOws."
 A little experience in the south- 1 west, in the period of summer rains.
 might lead Professor Moore to modi-
 fly his opinions again. He would
 find. for instance. that a torrential rain of an hour or two in the noun tains is sufficient sometimes to cause
 great floods in streams traversing
 the deserts. The high. barren moun- tains of Arizona present their precipi- tous sides to the rains and there is a | high percentage of quick runoff. On the other hand. the mountains that are covered by forests-especially the 1 undergrowth-hold the water in check
 and the runoff is slower; and the | floods. while lasting much longer i when coming from timbered drainage
 areas. are not apt to be so high. Over in New Mexico. ''Old Badly i mountain, which is some ninety miles
 northwesterly of Silver City. would ] be an interesting object lesson for Professor Moore. The northerly ! slopes of this mountain are covered | by heavy pine timber and dense I undergrowth. Even in the dry sea
 is no runoff from the surface until | the soil is thoroughly saturated. The affluents of the Gsla and of the San | Francisco rivers which rise on the
 northern side of Old Baldy" have a | steady flow and are not subject to violent fluctuations in volume. On the other hand, the southerly slopes Of this mountain present vivid con- trast to the northeriy side. The for ests are much lighter; the sheep hay
 ing destroyed the undergrowth, the soil is bare and dry. In dry seasons
 the soil has the appearance of failow
 fields Immediately following a tor ! rental rain. the waters rush down
 the sides of the mountain in great
 floods. carrying enormous quantities of dirt, which quickly becomes the fam ! otis silt of the muddy Gila. The af- fluents of the Gila which rise on the ! southerly side of the mountain be- come dry, or at most are mere rivu- lets in the dry season. Twenty years ago as all old residents of Arizona
 remember the GEa river was the dearest stream in the southwest. That was when the urfdergrowth on the other side of the mountains was still
 in existence. and before the present period of instant i:unoff.
 Indeed. Professor, Moore cuts the
 ground from under flis own feet when he qualities his statement by the suggestion that floods from forests
 occur only after the ground is every
 where saturated" Saturation of pre- cipitous mountain sides cannot occu
 if the soil is bare Of vegetation. The runoff is immediate
 Supposing always that forest Is forest indeed-a forest of trees shading a vegetation which covers the ground-we find therein natures ! reservoir of water whence the streams
 get their permanent flow.
 Professor Moore is more at home IT
 guessing at the weather from day to day than he is in dogmatizing or the relation of forests to floods.