THE CALCAREOUS CONCRETIONS OF KETTLE 
POINT, LAMBTON COUNTY, ONTARIO 
Ir cannot be said that the mechanics of the concretionary 
process in sedimentary rocks is well understood. The well- 
known spherical concretions of Kettle Point, at the southern end 
of Lake Huron, appear to throw some light on the problem of 
the mise en place of thoroughly exotic material, aggregated 
by this slowly acting molecular attraction. The purpose of the 
present paper is to illustrate the mode OLPOGCcUnLENce and ato 
indicate some facts leading toward the interpretation of these 
singular bodies. 
Logan has given us a concise description of the conditions 
at Kettle Point in the Geology of Canada, published in 1863." 
Reference is also made to them by Rominger;? but in neither 
case was actual illustration employed nor description given of 
perhaps the most remarkable characteristic of the concretions. 
About one half mile eastward of Kettle Point the highway 
from the town of Thedford decends sharply on a remarkably well 
preserved sea cliff of the formerly expanded Lake Huron, to 
the level of a gently sloping bench, cut in part in the drift, in 
part in the shales which underlie all this portion of Lambton 
county. At the Point itself the shales are seen to be wasting 
very rapidly on the face of a modern cliff from six to fourteen 
feet high and a few hundreds of yards in length. This condition 
is highly favorable to the exposure of the concretions, and one 
could hardly ask for more ideal sections for the study of struc- 
tural details in the bed rock. 
According to Logan these beds represent the equivalent of 
the Genesee Shale in New York state, which bears concretions 
of the same nature as those under consideration. Rominger 
tPp. 387, 388. 
2 Rep. Geol. Sur. Michigan, Vol. III, 1873-1876, p. 67. 
3Cf. HALL, Geology, Pt. IV, in the Nat. Hist. of New York, pp. 220 and 230. 
135 
