2i6 The Ottawa Naturalist. [March 



a terrace known as Johnston's Grove, in which Saxicava rugosa 

 and Maconia fragilis are abundant at a height of about three 

 hundred and fifty feet. These shells are also found in a cutting 

 at Carp Station, as stated by Dr. Ells. At Mohr's Corners, al- 

 ready referred to, there is a sand terrace which rises to a height 

 of four hundred and seventy-five feet and contains the above 

 shells in great abundance. In a cutting through a gravel bed 

 on the Electric Railway west of Hintonburg, Leda arctica, Saxi- 

 cava rugosa and a fragment of a Balanus were found. This is so 

 different from the other localities that it deserves s] ecial men- 

 tion. It is composed of a beach-like gravel, distinctly stratified 

 and well water-worn The pebbles are generally one to two 

 inches in diameter, with a small number of larger ones, the inter- 

 stices being filled with sand. Leda arctica is the most abundant 

 here, while at the other places named, only one specimen was 

 found. The shells are small but well preserved, and in some 

 cases the two valves are joined. The few specimens of Saxicava 

 rugosa which were found were also well preserved. This cutting 

 is on the edge of a terrace which extends back to the Ottawa, 

 Arnprior and Parry Sound Railway and is about two hundred 

 and thirty feet above sea level. 



TERRACES. 

 Terraces and old shore lines or beaches have been described 

 as occurring in many places along the Ottawa Valley. A good 

 example of a cut terrace may be seen on the Montreal road near 

 Green's Creek, at a height of about two hundred feet, but this 

 may be of fluviatile origin. At Chelsea there is a terrace at a 

 height of three hundred and fifty feet, and one round the base 

 of King's Mountain seven hundred and five feet high, North 

 of the west end of Muskrat Lake on the road leading to Beach- 

 burg, a fairly well defined shore-line occurs at a height of from 

 four hundred to four hundred and fifty feet. In many places 

 where the level tracts of Leda clay occur there are sloping 



