2I 4 



FORESTRY AND IRRIGATION 



May 



mounds, however, have been partially 

 or even entirely destroyed by fire, and 

 thus the water has found easier access 

 to the middle. By the destruction of 

 the mound, moreover, the tree is de- 

 prived of a large amount of fertilizing 

 material, which would otherwise grad- 

 ually be supplied in solution to the un- 

 derlying root system. 



Lastly, although the trees in being 

 burned are not injured in any way phys- 

 iologically, they are indirectly harmed 

 and their life is endangered by the 

 change in mechanical conditions caused 

 by the large excavations at the base. 

 These excavations often extend over 

 so large a part of the circumference 

 that considerable sections of the root 

 system are severed from the tree, thereby 

 weakening its principal means of sup-, 

 port in severe winds or storms. The 

 burn often extends so far inward that 

 the equilibrium of the tree is also en- 

 dangered. There is strong reason to 

 believe that this undermining of the 

 butt and weakening of the natural an- 

 chorage is the ultimate cause of the fall 

 and death of most bigtrees. Some day 

 the enormous column is rocked out of 

 its center of gravity and wrenched from 

 its natural cables. Almost all the large, 

 recently overturned trees will be found 

 to have extensive fire scars at the base 

 and the remains of a flat root system, 

 considerably reduced in circumference 

 by breakage. 



It has always been an interesting 



question whether the Sequoia groves, 

 that have been so much admired and 

 marveled at ever since the time of their 

 discovery, were approaching extinction, 

 or whether they were able to hold their 

 own in spite of gradual climatic change 

 and unforeseen vicissitudes. It is gener- 

 ally admitted that while the southern- 

 most groves show some indications of a 

 perpetuation of the species in the occur- 

 rence of a young growth of seedlings 

 and saplings, reproduction in the north- 

 ern groves is much less promising ; but 

 it is nat certain how far this is attribu- 

 table on the one hand to climatic con- 

 ditions, and on the other to the various 

 interferences by man, such as the lum- 

 bering of some of these groves and 

 adjoining forest areas, grazing by sheep, 

 and repeated forest fires. The question 

 of reproduction and its bearing upon 

 the future of this remarkable tree has 

 been touched upon from time to time by 

 various observers * with interesting and 

 valuable results. This is a wider ques- 

 tion. In the present note the writer 

 has ventured merely to direct attention 

 to the importance of protecting the older 

 trees against forest fires, on account of 

 certain harmful results which have 

 apparently heretofore escaped observa- 

 tion or been insufficiently emphasized. 



*See "On the Post-Glacial History of Se- 

 quoia Gigantea." John Mnir, in Proc. Am. 

 Assoc. Adv. Sci., XXV, pp. 242-253. George 

 B. Sudworth in Bulletin 28, Bureau of Forestry, 

 U. S. Department of Agriculture, p. 20. 



SEARCHING FOR WATERS UNDERGROUND. 



INTERESTING WORK NOW BEING CARRIED ON IN SOUTHERN 

 CALIFORNIA BY THE UNITED STATES GEOLOGICAL SURVEY. 



SOUTHERN California, a unique re- 

 gion, most widely known, perhaps, 

 for its climate, its oranges, and its beau- 

 tiful and hospitable homes, is rapidly 

 becoming a winter playground for the 

 people of the United States and Canada. 

 Among the features which make it most 

 attractive for the traveler of means or 

 of delicate health are its constant sun- 

 shine and clear, dry air. These neces- 

 sarily mean a limited precipitation and 



semi-arid climate; so that while our 

 eastern states receive of rain or snow 

 fall from 30 to 50 inches of water, dis- 

 tributed throughout the twelve calendar 

 months, the valley of southern Califor- 

 nia receives from 10 to 20 inches, prac- 

 tically all of which falls in the winter 

 months, from November to April. While 

 this assures an abundance of bright days, 

 it does not furnish sufficient moisture to 

 mature ordinary crops on the rich soil, 



