NOTICES OF OTHER SIMILAR REMAINS IN THE NEIGHBOURHOOD. 37 



In another : — 



Feet. 

 Lake Mud ........ i 



Chalky Boulder Clay i 



Alluvial Cravel and Peat ..... i 



Gravel 3 



More satisfactory evidence is found by returning to the outside 

 of the dam and taking its southern end. When the overflow was 

 transferred to this end, a broad and deep channel seems to have 

 been excavated for it. This channel can still be traced. Taking a 

 circuitous course, it enters the original bed of the stream about 70 

 yards below the dam. This channel was an effectual conductor of 

 the overflow for a very long time, and probably represents the period 

 of active occupation or use of the lake. The work of keeping this 

 channel clear and repairing the dam must have involved a continual 

 shifting of material and addition of new gravel to replace the waste. 

 There are various hollows in the vicinity which were perhaps made 

 for this purpose. 



A time, however, came when these labours ceased, and this 

 period of decadence has also left its mark. The channel was first 

 choked at about 30 yards from the dam, and the water then took 

 a new course across the enclosure made by the artificial channel 

 and the brook's original course. This new channel also succumbed 

 in course of time, and various other minor ones were made from time 

 to time, which have left faint traces. During this time, or in the 

 later years of the lake's existence, the dam was also neglected. The 

 process seems to have been that the overflow channel became 

 stopped at the dam, and lateral erosion commenced which gradually 

 extended along the dam for about 20 yards, and has reduced it 4 

 feet in height. The waste now lies behind the dam and forms an 

 inclined plane at that place to its summit. 



Finally there came a time when a breach was made in the dam 

 at its deepest part and the brook resumed something like its original 

 course. There are some considerations which lead us to believe 

 that this final drainage of the lake was effected a very long time ago, 

 and is, perhaps, only measurable by centuries. One consideration is 

 the road skirting the northern end of the dam. This has been worn 

 down about 4 feet since the breach was made — were the lake now 



