ECONOMIC FEATURES. 137 



GENERAL ECONOMIC FEATURES OF THE CRETACEOUS 



SYSTEM. 



The foregoing observations and conclusions are only introductory to the 

 great work which yet remains to be done in order to make the natural con- 

 ditions of the Cretaceous formations appreciated from a utilitarian standpoint. 

 To bring them properly before the attention of the people, it may be proper 

 here to give a brief statement of the economic features now under investiga- 

 tion. 



Soil Survey. — As the region under observation is essentially an agricul- 

 tural one, the first and most important economic problem is a study and defi- 

 nition of the great variety of agricultural soils within its bounds, in order to 

 increase their usefulness and provide for their preservation. With a few 

 unimportant exceptions of transported or alluvial soils existing in the river 

 bottoms of the region, these soils are mostly residual — i. e., the direct product 

 of the weathering of the underlying rock sheets — and consequently they pre- 

 sent a great diversity of qualities, varying with the underlying rock sheets. 

 Although, with a few minor exceptions, the soils are mostly calcareous, there 

 are many species of them, and each possesses some peculiar virtue or defi- 

 ciency for the growth of plant life. A geological map of the region, when 

 published, would accurately show the distribution of each of these diverse 

 soils, with descriptions of their qualities, thus placing our land values upon 

 a more stable and equitable basis, and enabling the farmer to use his soil for 

 plant growth in an accurate and definite manner, and to improve it, if neces- 

 sary, by an intelligent application of mechanical methods or fertilizers. This 

 classification of soils has advanced so far that in another year it is hoped a 

 final report may be made upon them for the northern area. 



The methods pursued in these soil investigations are as follows: The ex- 

 act geologic origin of the soil is ascertained, by minute observations of the 

 processes of disintegration of the rock or clay from which it is derived, with 

 especial reference to its mechanical condition, chemical composition, and na- 

 tive plant growth. 



The average depth and hygroscopic conditions and permeability are also 

 observed. The individuality of a soil having thus been determined, the 

 tracing of its extent is conducted coincident with the tracing of the rock 

 sheet from which it is derived. Due allowance is made for topographic 

 variations; the soils of the Grand Prairie region, for instance, being of 

 little depth except upon the high divides and mesas or in the valleys, the 

 valley slopes being mostly sterile. 



So important is this soil survey deemed that it is perhaps no exaggeration 

 to say that, with proper co-operation of our experimental stations, it will 



