242 ABORIGINAL REMAINS IN VERDE VALLEY. [eth ann. u 



surface, as a deep excavation in fairly even giouud would naturally 

 be made in a straight line. 



The face of the blutt' shows an even deposit of sand, without apparent 

 stratification, except here and there a thiu layer or faciug of mud occurs, 

 such as covers the bottom of the ancient ditch and also of the modern 

 ditch. Singularly enough, however, over the ancient ditch, about 5 

 feet above its bottom, there is a stratum of sand and gravel, and on 

 top, withiu a few inches of the surface of the ground, a thin stratum 

 of mud. This mud stratum extends only about 8 feet horizontally 

 and is slightly hollowed, with its lowest part over the center of the 

 ditch. The gravel stratum also was laid down over the ditch, is tilted 

 slightly southward and occurs in two layers, together about a foot 

 thick. It first appears a few feet south of the point where the main 

 ditch enters the bluff and over the ditch both layers are distinctly 

 marked, as shown in plate xxxviii. Both layers are clearly marked to a 

 distance of 4 feet north of the northern side of the main ditch ; here 

 the lower layer thins out, but the upper laj^er continues faintly marked 

 almost to the edge of the small ditch. At this point the gravel sti-atum 

 becomes pronounced again and continues over the small ditch, almost 

 pure gravel in places, with a decided dip westward. At a. i^oint just 

 beyond the northern side of the small ditch the gravel layer disappears 

 entirely. 



The occurrence of this gravel in the way described seems to indicate 

 that the ditch was built along the slope of a low hill forming the edge 

 of the bottom land at that time, and that subsequently detritus was 

 deposited above it and over the adjacent bottom laud forming a smooth 

 ground surface. Against this hypothesis it must be stated that no 

 evidence whatever was found of more than a single deposit of sandy 

 loam, although the exposures are good; but perhaps were an examina- 

 tion made by a competent geologist some such evidence might be 

 developed. 



There is one fact that should not be lost sight of in the discussion, viz, 

 the very low elevation of the ditch above the river. The Yerde is, as 

 already stated, a typical mountain stream, with an exceptionally high 

 declivity, and consequently it is rapidly lowering its bed. If, as 

 already conjectured, the water for the aucient ditch was taken from the 

 river but a short distance above the point where remains of the ditch 

 are now found — and this assumption seems well supported by the 

 character of the adjacent topography — the slight elevation of the bed 

 of the ditch above the river would indicate that, in the iii'st place, 

 the ditch was located, as already suggested, along the slope of a hill, 

 and in the second place, that the ditch was built at a period of no great 

 antiquity. The occurrence of the high bluff under which the ditch now 

 passes does not conflict with this suggestion, for the deposition of the 

 material composing it and its erosion into its present form and condi- 

 tion may be the result of decades rather than of centuries of work by 



1 



