150 H. L. FAIRCHILD PLEISTOCENE GEOLOGY OF NEW YORK STATE 



to the idea that all typical kames are formed by streams debouching into 

 water bodies, and sometimes by subglacial streams nnder hydraulic pres- 

 sure. Streams debouching on the land would naturally produce either 

 outwash plains or valley trains. The fact that basins or kettles, believed 

 to be due to melting out of buried ice blocks, are usually abundant in 

 areas of kames seems to prove that the materials were laid down in stand- 

 ing water in close association with the stagnant ice-margin, either on 

 the ice or in hollows and valleys and reentrants in the ice. 



Extraglacial: outwash plains. — These are the gravel and sand deposits 

 spread out in front of the glacier by the outflow of the glacial streams 

 and which can not be classed on the one hand as deltas or on the other 

 as valley trains. Water-laid drift in facial contact or close association 

 with the moraines and which can not be distinguished either as delta, 

 kame, or valley train may safely be put in the indefinite class of outwash 

 gravel plains. North of the divide where built in lakes they grade into 

 deltas and kames. South of the 'divide they constitute most of the valley 

 fillings, specially of the broader valleys which lay athwart the direction 

 of ice-flow. 



A not uncommon feature of the gravel plains, and one which shows 

 the close relation to the glacier front, is the existence of ice-block kettles. 

 The term "pitted plain" has been applied to the sand plains with numer- 

 ous kettles. Another feature indicating their genesis is the preservation 

 in some cases of the ice-contact slope. The outwash sand and gravel 

 plains are more common in the southwest part of the State and in the 

 Mohawk Valley. In the highlands the drainage was too free and vigor- 

 ous. In the Champlain-Hudson Valley, lower levels, the sealevel waters 

 distributed the glacial stream detritus, or it was buried under the deluge 

 of sand contributed by the rivers since the ice disappeared. The very 

 extensive sand plains on both sides of the Hudson Eiver and Lake Cham- 

 plain — for example, the Saratoga District — must be classed as marine 

 deltas ; but on the walls of the great valley above the marine plain Wood- 

 worth has noted ice-contact slopes of glacial outwash deposits. In the 

 Susquehanna District Tarr found numerous plains of this class. 



Extraglacial: valley trains. — South of the divide, where the drainage 

 had free escape, some detrital filling of the valleys is common and occa- 

 sionally abundant. The high-level floodplains along the valley sides and 

 the elevated deltas of lateral tributaries testify to the glacial floods and 

 their burden of detritus. The deposit by glacial flow is, of course, inter- 

 mingled with and in places buried under land-stream detritus. The val- 

 ley trains may be regarded as heading in outwash plains, and one might 

 regard the glacial gravel deposits in the entire length of the valleys north 



