1 4 o NITRATE DEPOSITS 



the decomposition of bat guano. By leaching of the soluble salts from 

 the guano, the nitrates are removed and may be concentrated in other 

 parts of the cave or distributed elsewhere. 



Because of their solubility, it is not to be expected that any large ac- 

 cumulation of nitrates can take place excepting in protected places such 

 as caves, or in arid countries where there is very little rain. In such 

 countries, however, there is very little vegetation, and consequently the 

 organic processes which are of such importance in bringing about fixa- 

 tion of nitrogen in humid countries are able to operate to a much less 

 extent in desert regions. "\Ye thus find that in the soil of such regions 

 the total nitrogen present is usually much less than in soils which sup- 

 port a good vegetation. 



On the other hand, the soils of desert countries have marked nitri- 

 fying powers, with the result that a large percentage of the nitrogen 

 actually present is converted into nitrates. Furthermore, owing to the 

 low percentage of organic matter present and to the porous nature of 

 desert soils the anaerobic dentrifying bacteria are not so active in chang- 

 ing nitrates into free nitrogen, while the lack of vegetation prevents their 

 convertion into protein nitrogen. The nitrates which are formed are 

 thus enabled to accumulate, and either remain in the soil or are trans- 

 ferred by underground waters to other localities where they may be con- 

 centrated by evaporation of the water at the surface of the ground. If 

 there has been any introduction into desert localities of organic matter 

 from external sources, as may be brought about by the droppings or re- 

 mains of animals, the accumulation of nitrates may be correspondingly 

 increased. It thus happens for the reasons given that the largest 

 nitrate deposits are found in desert regions. 



In this country few nitrate deposits are to be found apart from those 

 of cave origin. The most extensive so far known occur in San Ber- 

 nardino and Inyo Counties, California, along the shore lines or bed 

 beaches of what was supposed to be a former sea, but which is now geo- 

 logically known as Death Valley. The region popularly known as Death 

 Valley is that portion of the valley proper which is below sea level. The 

 territory covered by nitrate beds has been estimated to cover an area of 

 about 35,000 acres. Through erosive agencies the clay beds in which the 

 nitrates were deposited have been worn into buttes and ridges of charac- 

 teristic shape and color. The hills so formed vary from only 50 feet 

 high to over 300 feet. Samples taken from the niter-bearing strata in 

 the hills, and exposed by erosion, vary all the way from a trace to more 

 than 50 per cent, of nitrates. It is generally agreed that these deposits 

 have not been formed in situ, but have resulted from the concentration 

 of nitrates formed from the decomposition and nitrification of animal 

 and plant life which must have existed in the region at the time that the 

 valley was filled with water. Owing to the limited distribution of these 



