106 



The Ottawa Naturalist 



[Vol. XXXII. 



is floored with stoneless marine clay, its surface 

 standing at a slightly higher level than the clay 

 plain in the Bonnechere valley into which it merges. 

 The length of the combined clay plains from Ren- 

 frew to the furthest point in Bromley is 20 miles 

 and its widest extent is 6 miles. The greater part 

 of this land was sown with spring wheat in 1918 

 with excellent results. 



Douglas is a small trading and social centre for 

 the neighboring farming community. Its situation 

 on the southern slope of a low ridge overlooking 

 the valley makes it a desirable site for residential 

 purposes, but it is doubtful if it will expand in- 

 dustrially owing to its proximity to Renfrew. 



larged its passages until a considerable volume now 

 issues from a cave on the north side of the river a 

 short distance below the foot of the falls. There are 

 a series of lofty caves in the cliffs below the falls, in 

 addition to the one through which the stream dis- 

 charges and probably formed in the same manner. 



The lower limestone beds in the cliff are shaly 

 in characted and consequently very friable and 

 easily worn by the action of running water. The 

 upper beds are less easily disintegrated being massive 

 and more compact in texture, and these form the 

 roofs of the caverns. 



Masses from the upper beds, however, are con- 

 tinually falling, according as the lower shaly beds 



Fig. 3. The highly cultivated clay plain west of Renfrew, looking toward the southern 



upland border. 



The clay land extends a few miles west of 

 Douglas, but only in a very narrow strip along the 

 river banks and ceases entirely near the fourth 

 chute. 



There is an extensive sheet of glacial outwash 

 gravels at Caldwell station on the Grand Trunk 

 railway four miles west of Douglas. The railway 

 company has worked out a large excavation in using 

 these gravels for ballast, so that good sections show- 

 ing their character and structure can be observed. 



FOURTH CHUTE. 

 At the fourth chute the Bonnechere river makes 

 an abrupt descent of about 38 feet over ledges of 

 flat lying limestone. A portion of the water above 

 the falls finds its way down through lines of weak- 

 ness in the limestone formation. By the processes 

 of erosion and solution the running water has en- 



on which they depend for support become under- 

 mined by the water. The river breaks up the fallen 

 masses and disposes of them within a comparatively 

 short time, so that quite an ampitheatre has been 

 carved in the cliffs in post glacial times. 



These caves are an impressive example of the 

 rapid erosion of comparatively soft rocks by running 

 water, and the process is here revealed by which the 

 removal of the greater part of the vast layer of paleo- 

 zoic limestones and shales which formerly existed 

 in the Bonnechere valley was effected. 

 EGANVILLE. 



Eganville the ultimate village in the valley is sit- 

 uated on the fourth water power of the Bonnechere 

 river, 23 miles west of Renfrew. 



Mr. Alexander Murray, of the Geological Sur- 

 vey, when making the survey of the Bonnechere 



