hershey.] The River Terraces of the Orleans Basin. 



448 



sides of the mine by three to eight feet of reddish brown sandy 

 silt, which in places is nearly free from rock fragments and in 

 other sections has small angular and rounded fragments. It 

 is a marked horizon throughout the mine. Along the outer edge 

 it is thickest and constitutes the surface formation. It appears 

 to have formed a comparatively even terrace at about eighty-five 

 feet above the river. Along the inner side of the mine it is 

 overlaid by slate debris of gray color. This has slidden from 

 the steep slope back of the mine and is disposed in the form 

 of two rather sharp fans, in the axis of each of which the 

 material reaches a thickness of thirty feet. But these are land- 

 slides and not torrent fans. In one the material is thoroughly 

 broken up, but in the other large masses of the slate remain 

 practically unbroken, from which the exposure resembles 

 a bed-rock bluff. Curiously, the gravel and red silt pass under 

 this mass of rock, at first sight startling the observer. Near the 

 border of the deposit contorted slate in a lied only six feet thick 

 overlies the red silt with a nearly even line of contact. 



The lower channel on this point has an average width of 

 only 150 feet, and its floor has a height above the river of forty 

 feet. The debris piles left on the floor include a number of 

 rather large boulders. The bank at the head of the excavation 

 consists of about twenty-five feet of moderately coarse gravel 

 overlaid by a few feet of brown dirt, the surface of which is 

 that of the terrace. Near the river there are no remnants of 

 the surface of the terrace, but it was probably sixty-five or 

 seventy feet above the stream. 



Back of the village of Orleans this terrace spreads out into 

 a broad plain possibly seventy-five acres in extent. The outer 

 border is comparatively even (except for shallow ravines) at a 

 level which at the cemetery is nearly seventy-five feet above the 

 river. The surface rises toward the hills in a series of gentle 

 undulations. 



Between the Salstrom Mine and the Salstrom Ranch Flat 

 there are about eight acres of the "seventy- foot terrace," which 

 however, is here probably nearer 100 feet than seventy feet above 

 the river. 



The 45-Foot Terrace. — Directly opposite the Markusan build- 



