PLEISTOCENE GEOLOGY OP MOOERS QUADRANGLE 19 



rock as fast as they were loosened. Such excavations as " Pox- 

 house gully." " Rattlesnake den," and " Leadmine gully " near 

 Altona, if not existent previous to the time of the stripping, 

 would seem to owe their origin to streams flowing down the 

 natural slope of the rocks rather than to glacial torrents. 



At the southeastern end of the area, about a mile northeast 

 of Robinson, there is a deep trench not shown by the contours 

 of the map. This trench extends partly through the till-covered 

 rocks about the southern margin and in places is as much as 50 

 feet deep. At the time of my visit in 1902, there was a small 

 stagnant lakelet held in by driftwood near the eastern part of 

 the channel. Westward the channel passes into a partly drift- 

 filled vale with kamelike habit, suggesting the presence of the 

 ice sheet during the cutting of the gorge. It is probable that the 

 channel is due to the escape of waters from the head of Robinson 

 brook at a time when the ice front was passing away from the 

 vicinity. That the channel represents glacial drainage rather 

 than natural stream work is shown by the manner in which it 

 cuts across the low. spur of the sandstone shown by the north- 

 ward loop in the 900 foot line on the map. 



A more pronounced channel with a remarkable pool is found 

 at Dead sea. This lakelet is apparently one of the group of 

 abandoned waterfall pools, for the reason that no permanent 

 stream capable of making so large an excavation now traverses 

 the area [pi. 7-10]. The waters which produced the Dead sea 

 rock basin evidently flowed eastward; the same is true of those 

 which produced the channel near Robinson. All the ascertained 

 phenomena from this district bearing on direction of water 

 movement show that it ran eastward across the col at " the 

 Gulf" south of Covey hill; southward along Stafford's and 

 Blackman's rocks; thence southeastward past Irona and over 

 i lie Altona Flat Rock district. 



In the case of the Altona Flat Rock tract, it is to be noted that 

 bared ledges begin on the west at a point where the retreating 

 front of the ice sheet might have diverted the Big Chazy river 

 to the eastward along the ice margin; and, whether or no waters 

 came along from the west, including those of the north branch 



