424 E. S. MOORE 
however, some silica in small grains of various sizes, some chal- 
cedony infiltrated along the lines between the bodies, and in some 
Fic. 9.—The algal concretionary limestones on Tookcarak Island. The largest 
concretion is about 15 inches in diameter. 
Fic. ro.—Algal concretionary limestone on Tookcarak Island. The largest con- 
cretion is 14 inches in diameter. 
places a little carbon may be found under the microscope, especially 
along the surface separating the concentric rings of growth. This 
