Thus the so-called granite areas of the Sierra Nevada of California are largely occupied by a rock containing, besides quartz, chiefly soda-lime feldspar and some hornblende, and scarcely any mica. It is more properly a diorite (grano-diorite); the soils formed from it are rather poor in potash, not strongly calcareous, and quite poor in phosphoric acid. On account of the small proportion of hornblende (unusual in diorites), these soils are light-colored (not “red”), and bear a growth of small pine instead of the usual oak growth of the lower Sierra slopes. What is said of granite soils is also generally true of those formed from _Gneiss_, which is composed of the same minerals as granite, but has a slaty cleavage and on that account when upturned on edge, weathers rather more rapidly than most granites. Owing to the frequent occurrence of lenticular masses of quartz in gneiss, its soils are more commonly of a siliceous nature than are those of the true granite regions, and not as “strong” as the latter. This is the more true since gneiss often passes gradually into _mica schist_, which, being a mixture of quartz and mica only, not only weathers very slowly but also supplies but little of any importance to plants, to the soils formed from it. Such soils would mostly be absolutely barren but for the frequent occurrence in the rock, of accessory minerals that yield some substance to the soil. Yet it remains true that inasmuch as gneiss and mica-schists are among the rocks in which mineral veins most commonly occur, the proverbial barrenness of mining districts is very frequently traceable to these rocks. The same may be said of some of the related rocks, such as gabbro, minette and others. Normal _diorite_ consists of hornblende and soda-feldspar, with more or less quartz. The soils derived from certain diorites of the Sierra Nevada of California have just been referred to. But these granite-like diorites are on the whole exceptional; it should be added that the (diabasic) “greenstones” of the Eastern United States and of the Old World, which are usually much finer-grained, do not form the mass of fine, angular debris constituting the subsoil in the Sierra Nevada, but weather into rounded masses and fine-grained soils possessing, on the whole, a fair fertility, though liable to contain an excessive proportion of silex in various forms.