The Central Great Plains 



397 



dence that this is the case, excepting 

 locally where there are numerous wells. 

 Individual wells often diminish in effi- 

 ciency owing to leakage, clogging, and 

 other causes, but ordinarily new wells 

 in the same vicinity show the same 

 pressure and flow as were found in the 

 older ones ; but it is probable that if 

 this large flow is permitted to continue 

 the available volume of artesian supply 

 will eventally be greatly diminished. 



The source of water is believed to be 

 in the Black Hills and in the Rocky 

 Mountains, for the sandstone appears 

 to be a continuous stratum or a series 

 of strata, permeable throughout, and 

 containing water which to the east has 

 much of the initial head or pressure due 

 to the high altitude of the zone of in- 

 take on the mountain slopes. There 

 are extensive areas in central South Da- 

 kota in which the underground waters 

 have not yet been developed. Appar- 

 ently in these areas the Dakota sand- 

 stone lies deep, but not at an impracti- 

 cable depth for well-boring. Probably 

 further drilling will show that flowing 

 waters may be obtained all the way up 

 Cheyenne Valley and its two branches 

 to the Black Hills, and up the valleys 

 of White, Bad, and Owl rivers nearly 

 to longitude 102 0 . 



The Central Great Plains region pre- 

 sents considerable variety of climate. 

 To the east, on the plains, the precipi- 

 tation varies from moderately humid to 

 nearly arid, the change taking place 

 gradually from east to west. To the 

 east there are 40 inches of rainfall per 

 year, while to the west, in the region 

 adjoining the Rocky Mountains and the 

 other ranges, there are less than 12 

 inches over an area of considerable ex- 

 tent. To the east the precipitation is 

 ample for crops, and that portion of the 

 region is one of the greatest producers 

 of corn, wheat, and other agricultural 

 products in the world, while to the west 

 there are broad tracts in which no crops 

 can be produced without irrigation. 

 On the mountains in the western por- 



tion of the area there is locally increased 

 precipitation, which in many areas is 

 sufficient for agriculture. The amount 

 of water that falls in the arid area is 

 enormous when the number of cubic 

 feet per square mile is calculated, but 

 much of it comes in very heavy showers, 

 after long intervals of drought, often 

 with severe hot winds. If a portion of 

 the rainfall could be stored, much of it 

 could be used for irrigation. 



DEFORESTATION AND CLIMATE 



WHETHER forests exercise a per- 

 ceptible influence upon the cli- 

 mate is a very old question, and even 

 today it is not definitely settled. At a 

 recent session of the German Meteoro- 

 logical Society at Berlin a lecture on 

 " Deforestation and Climate " was de- 

 livered by Doctor Hennig, from which 

 the following extracts are taken : 



In many countries a drying up of the 

 climate has occurred, which is shown 

 perhaps most strikingly in almost the 

 whole of Africa. That deforesting has 

 assumed constantly growing proportions 

 in almost every part of the world is still 

 more apparent. The climate of Greece, 

 where today only 16 per cent of the 

 area is covered with forests, has de- 

 teriorated. An increase of temperature 

 and decrease of rain are noted, com- 

 pared with ancient times, especially in 

 Attica, which was thickly covered with 

 forests about 3,000 years ago, and where 

 hardly any rain now falls, while the 

 heat in the open air attains a degree 

 which would make the ' ' Olympian 

 games" almost an impossibility. A 

 similar condition exists in the Penin- 

 sula of Sinai, where thousands of years 

 ago the people of Israel lived in a lux- 

 uriant and fertile country and where 

 today only forestless deserts abound. 

 Palmyra, also once a flourishing oasis 

 in the Syrian desert, presents today only 

 a desolate waste of stones and ruins. 

 In Mexico, where the Spaniards cut 

 down the forests in the mountains, 



