2 BULLETIN 502, U. S. DEPARTMENT OF AGRICULTURE. 
wet ground usually occurring near an underlying shale ridge, point, 
or knoll which discharges water into the soil immediately surround- 
ing it. 
The possibility of reclaiming the water-logged and alkaline shale 
lands has been demonstrated in numerous instances; the purpose of 
this bulletin is to explain how and why the shale enters into the 
problem and to present the principles and methods upon which the 
reclamation of this type of land depends. 
GEOLOGICAL FEATURES. 
In the drainage of shale lands some knowledge of the underground 
formations is essential, as the seepage water often is under pressure 
and the problem is similar in some respects to one of developing an 
artesian supply. The water may move for considerable distances at 
depths that can not be reached by drains and may appear on the sur- 
face at some lower point. Ordinary methods of drainage fail because 
of the pressure and the resulting upward movement of the water. A 
proper solution of the problem requires a careful study of the source. 
and direction of ground-water movement. Obviously, this necessi- 
tates a knowledge of the strata carrying the water. 
The area to which this bulletin pertains is situated in the Rocky 
Mountains and en the high plateau areas immediately adjacent. The 
land usually is at a high elevation, the slopes steep, and the topog- 
raphy very rough. The rivers usually are hemmed in by high rock 
bluffs where they emerge from the mountains into valleys that are 
more open and gentle in slope. These valleys often are characterized 
by a sharp ascent to a gravelly mesa on one side and by a long 
gradual slope on the other side. Some distance back from the stream 
the ascent is broken by terraces of gravel or sand, or by tracts of 
clavey “bad lands,” and here and there by rocky cliffs and mesas. 
Shale is a finely stratified or laminated rock, formed from the strati- 
fication of clay, silt, or mud. In some of the so-called paper shales 
(Plate III, fig. 2) there are as many as 30 or 40 lamine to the inch, 
each representing a separate stage of stratification. 
Numerous varieties of shale structures are encountered which in- 
fluence the movement of the underground water; however, this dis- 
cussion is limited to the following three distinct types that have a 
wide range: Type No. 1, hard, calcareous shales that have suffered 
little or no displacement; type No. 2, shales, the layers of which dip 
very steeply ; and type No. 3, shales in which the layers are horizontal 
or nearly so, but which have been subjected to great pressure. 
Shales of the first type need little description. Being hard, poorly 
_ laminated, and lacking fissility, they more nearly represent the popu- 
lar conception of shales which classes them among the less pervious 
geological strata, They probably are not capable of containing more 
