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NOTES ON CONCRETIONS 
Concretions are most commonly spheroidal, or nearly so in 
shape, and range in size from that of a grain of sand to twenty 
and thirty feet in diameter. 
1. On the coast of Arisaig, N.S, in the argillaceous slates 
and shales of the Clinton formation, slightly flattened spher- 
oidal forms are abundant. Two of these, about two feet in 
diameter when broken through the centre, showed no concentric 
layers or nuclei, while many others, varying in size from the 
eighth of an inch to two inches in diameter, contained invariably 
a nucleus ; sometimes a grain of sand, but generally the brachio- 
pod, Lingula oblonga, Hall. 
2. The largest concretions seen by the writer were found in 
the Fox Hill and Pierre shales and clays of the North-West, 
and a very interesting exhibition of giant forms may be seen 
three miles north of Irving station-house on the Canadian 
Pacific Railway. Here, huge boulder-like spheroidal and ovoid 
concretions once held in the rocks but removed by great 
denudation (probably in the glacial epoch, for glacial striz are 
seen on some of the flat beds), stand out in bold relief, resting 
on the flat and upturned edges of shales and sandstones ; and 
on the top of one of them, about twenty feet high, an eagle had 
built its nest of buffalo-bones and the roots of the wild sage, for 
want of a more elevated situation, which does not occur in this 
locality. 
In composition they appear to be chiefly argillaceous and 
caleareous sandstones. Many of them have fallen to pieces, and 
the debris shows that they have been formed in layers which 
increased in thickness from the centre outward. Portions of the 
beds from which they were derived were found enclosed in 
several of them, and the stratified pieces of the bed-rock were 
found to be prolific in fossils. Among the genera and species 
found in these were: Lingula nitida ; Protocardia subquadrata ; 
Liopistha undata, ete. 
3. Mr. R. G. McConnell, of the Geological Survey, describes 
