THE STRUCTURE OF THE CLAY. 705 



THE LATERAL PASSAGE OF THE CLAYS INTO THE HIGH TERRACE SANDS. 



At the soutli end of the Camp Meeting cutting (PI. XV, p. 678) the 

 whole thickness of the cutting- was in clay and the plane of junction dipped 

 north with a low angle, so that the clays ran far under the sands and dis- 

 appeared below the level of the cut. The sands were part of ;i delta or 

 bar front, advancing southward and dipping sharply in this direction in 

 quite thick layers which at the bottom of the slope became horizontal, thin- 

 ning rapidly and running out between the clay layers, becoming finer 

 grained and disajipearing or merging with the coarser portion of a layer ot 

 the clay. On the other hand, some layers of the clay ran up the slope 

 bet^^'eeu the sand layers for a distance, becoming coarser and merging with 

 an upper and finer portion of the sand layer. 



THE PASSAGE OF THE CLAYS INTO THE SANDS ABOVE. 



The delicate partings of sand described above (p. 704) increase in 

 number and in thickness as one approaches the upper surface of the clay, 

 and finally efi'ect the passage of the one into the other. 



In the river Ijank below Hadley, the locality which for the most part 

 furnished the type of the preceding descriptions, the upper portion of the 

 clays has been can-ied away by the river, and its sands rest ixnconfonnably 

 upon the eroded surface of the clays. The true passage beds are best 

 exposed at the extreme south end of the Camp Meeting cutting (PI. XV, 

 p. 678). 



Nine feet below the upper surface of the clay these partings are one- 

 sixteenth of an inch thick, of coarse red sand, and are very frequent, so 

 as to give the blue clay a reddish tinge. This continues upward for 3 

 feet, when a 4-inch layer of coarse red sand intervenes, which is followed 

 by a band 5 feet thick, where the red sand and clay, alternating in fine 

 but regular layers, are in about equal qxiantity. The Avhole is capped by 

 another thick layer of red sand, which grades into the ordinary buff flood 

 sands, here only 4 feet thick. 



Opposite the Hatfield Hotel begins a long, naiTOw remnant of the old 

 lake bottom, which, by a curious freak of the river, has been left intact, 

 while the river has cut away on all sides of it. This preserves the old sur- 

 face of the clays and the passage beds into the sands above. There is here, 

 within 4 feet, a very gradual passage from the fine clays into fine, white 



MON XXIX 45 



