648 E. M. KIXDLE CANADIAN PLEISTOCENE CONCRETIONS 



Plate 9.^ — Concretions 



About one-half natural size. 



Figures 1 and 2. — Two views of an angular piece of limestone partially cov- 

 ered- by a concretionary growth. A cross-section of the specimen 

 made by breaking is shown in figure 1 and a side view of the 

 opposite end by figure 2. 



Plate 10. — Concretions 



Figure 1.— This doughnut-shaped concretion shows the smooth surface char- 

 acteristic of the slightly weathered "claystones" of the Lower 

 Pleistocene clay of the Ottawa Valley. 



Figures 2-5. — These concretions represent the type to which the term marlekor 

 will be confined. Note the shrinkage cracks shown by figure 2 

 and figure 5 ; also the irregular surface displayed by all of them. 

 From the middle division of the Pleistocene clays south of Wil- 

 sons Corners 3 miles, Province of Quebec. 



Figures 6 and 8. — These specimens show the thin shell of partially indurated 

 clay which adheres to the concretions when removed from the 

 bed in w^hich formed, Ottawa River below Greens Creek. 



Figure 7. — Concretion attached to the side of a pebble, lower clay, Ottawa 

 River below Greens Creek. 



Plate 11. — Concretions 

 Seven-eighths natural size. 



Figures 1-4. — Root concretions composed of sand cemented by calcium car- 

 bonate. Specimen number 2 has been ground to show the chan- 

 nel originally filled by the root. From the sand beds at Rideau 

 Junction, Ontario. 



Figures 5-10. — Pseudoconcretions composed of soft blue clay filling irregular- 

 shaped vertical tubes in the sand beds, Rideau Junction, Ontario. 



Figures 11 and 12. — Side and cross-section of a root-shaped concretion con- 

 sisting of indurated clay, brick clay pits southwest of Billings 

 Bridge one-half mile. 



Figures 13 and 14. — Soft or very slightly indurated concretions with a root 

 nucleus. Figure 13 is a ground specimen showing the concentric 

 orange-brown colored zones which surround the axis. Upper 

 clay beds southwest of Billings Bridge, Ottawa, one-half miie. 



Plate 12. — Concretions 



Figures 1 and 2. — Concretions (rhizoconcretions) formed in a bed of uncon- 

 solidated shells by calcium carbonate cementation of shells ad- 

 jacent to roots. Note the root nucleus in figure 1. Pleistocene 

 beds, Saint Augustine, Florida. 



