THE FORESTS AND DESERTS OF ARIZOXA 213 



a very general and interesting phenomenon tliroughout tlie.se 

 woods, furnishing not only most i)leasing vistas hut opportunity 

 for pasturage and agricultural use. Their soil is usually rich 

 black loam washed from the surrounding hills, rather compact 

 and liable to a wide range of moisture conditions on account of 

 deficient drainage, and hence inimical to tree-growth, l)ut readilv 

 supporting a greensward of grass. In wet seasons tliese depres- 

 sions sometimes turn into lakes. iMormon hike, wl^cii wo pass, 

 is such a prairie, some five miles long and one to two mik's wide, 

 which, when the Mormons arrived there, had tiie appearance 

 of a rich meadow, inducing them to settle and go into dairy farm- 

 ing ; after a few years the glade filled up with water and became 

 a lake ; in 1895 it was all dry except a small renniant of water in 

 the lowest depression. As these patches of fertile land, forming 

 about 15 to 20 per cent of the forested area, are destined to be- 

 come objects of agricultural development — they have begun to 

 be so used — and in that way to be helpful in the rational man- 

 agement of the surrounding forest country, it would be of inter- 

 est to experiment as to their best treatment; many of them hy 

 judicious ditching, by which the moisture extremes may l)e 

 abated, can undoubtedly be made to produce various crops be- 

 sides the potato and alfalfa or oats which the short season and 

 the cold condition of the soil now permit. 



As we proceed we presently pass a most forbidding spot, where 

 the limestone soil is covered with black blocks of lava, giving 

 rise to soils locally known as malapai, corrupted from the Span- 

 ish mal pais, bad lands, although the soil is not so bad after all, 

 at least for tree-growth. One of the great lava fields of the world, 

 made up of basalt and trachyte, extends from San Francisco 

 mountains southward and northward, covering fully 2().(XM) 

 square miles with its overflow. 



As we progress through the forest we learn from the ditlerences 

 of soils and consequent differences in develo]tment of the trees 

 something of the geology of this plateau. Arcluean, Silurian, 

 Carboniferous, Juratrias, Cretaceous, and igneous rocks are found. 

 Three soil formations are readily recognized— limestone here, 

 sandstone there, and over both, irregularly, the decomposed beds 

 of lava which have overflowed thousands of square miles, giv- 

 ing rise to the malapai. So i\ir ns tree-growth is concerned, wher- 

 ever the decomi)Osition of the lava l^locks has been thorough 

 and limestones have added their quota, the soil is by no means 

 unfavorable. The limestone soils seem to jiroduce tiie best 

 timber, the sandstone soils the poorest. 



