28 



BULLETIN 502^ U. S. DEPARTMENT OF AGRICULTUEE. 



From a large number of borings the topography of the underlying 

 shale was determined as indicated in figures 4 and 5. Shale was 

 found near the surface on three-fourths of the tract, but no shale 

 nor water could be found at a depth of 12 feet at the southwest 

 corner, and the alfalfa there was in good condition. The strata of 

 the shale underlying the tract are nearly vertical and badly broken. 



Proposed Ti/e Drains 

 Grouncf Surface 

 Sha/e Surface-- 

 Wafer Surface-- 



SCALE OF FEET 



100 50 100 200 



Fig. 4. — Four-acre tract near Canon City, Colo., showing plan of drainage. 



The shale is comparatively soft, from dark blue to reddish brown in 

 color, and carries considerable water. The Avater apparently comes 

 from the north, following along the joints in the shale strata, 

 although it is believed that the extreme Avet condition of the north- 

 west corner is due in part to the movement of the water in the top 

 soil from the tract to the Avest, which also is very wet. The under- 

 lying shale ridges on this tract are not AA'ell defined; they are broad 

 and flat. A rather broad shale ridge comes in at the northwest 



