194 TRANSACTIONS OF THE 



upon by vines), while the hardpan is relatively poor in that sub- 

 stance. The lime percentage is the same in both, and is ample. In 

 phosphoric acid, both alike are above the limit of deficiency, but the 

 supply is not large, and will probably be the lirst needing to be 

 replenished when the soil becomes "tired." Still, in view of the 

 depth and perviousness of the subsoil, it may be long before this con- 

 dition will make itself felt in the case of deep-rooted plants, such as 

 vines and fruit trees. 



Two other soil varieties are found in the colony, differing from the 

 one analyzed mainly in the greater proportion of sand, which in one 

 case is very coarse. The latter overlies the hardpan to the depth of 

 four or five feet, and is reported to have shown an especially thrifty 

 growth of the vines planted, though the latter have done well on all. 

 Probably for the first years at least, the thriftiness of the vines will 

 be in direct proportion to the depth of the surface layer of soil. 



SOIL FROM THE CAJON VALLEY, SAN DIEGO COUNTY. 



The Cajon Valley, which has come into wide notice only within a 

 year or two, lies fourteen miles inland east of San Diego City, and 

 may be approached either through Choya Valley or across the mesa; 

 the highest elevation on the route being about 700 feet. The valley 

 is of an irregularly rectangular shape, and is surrounded on all sides 

 by hills, which on the north side form a gradually ascending rolling 

 country, while elsewhere they are more abrupt; thus, with the angular 

 form of the valley, giving rise to the name (signifying a box). The 

 San Diego River valley forms the northern edge and the lowest por- 

 tion of the plain, about 350 feet above sea level; from this there is 

 ascent to 500 feet at the southern border, four miles away. There is 

 also a slight slope from the east and west sides toward the center; 

 the greatest diameter in this direction being five miles. 



Several smaller valleys, among them Sycamore Canon, come from 

 the sides, but none of these have any permanent waterwaj^ The river 

 valley is well timbered with willow, sycamore, oak, and cottonwood. 

 The rest of the valley is treeless. 



The prevailing soil outside of the river valley is an orange or red- 

 dish-brown sandy loam, varying in depth from twenty inches to three 

 feet without sensible change, the latter being the more common depth. 

 The soil stratum is underlaid by a more compact clayey material, 

 which, however, easily softens in water, and is readily worked when 

 at all moist. This "hardpan," as it is sometimes called, is from 

 fifteen to twenty-five feet in thickness, and is easily penetrated by the 

 roots of trees and vines. Beneath it water is found in wells at depths 

 varying from seven feet at the north end to thirty feet at the southern 

 border; the water supply being about the same through the year, 

 and, with but two or three exceptions, of good quality. The latter 

 occur near the northwestern corner of the valley, where there are 

 some alkali spots on a heavy dark adobe soil, of which small tracts 

 are found on the western slope. 



The analyses of the red soil, taken to twelve inches depth, and that 

 of the subsoil, taken at three feet depth, both on the Cajon Land 

 Company's tract, resulted as follows: 



