77S T. C. BROWN OOLITES AND OOLITIC TEXTURE 



Explanation' of Plates 

 Plate 26. — Micro-sections of oolitic Structures 



J^GTJBE 1. — "Kettering Stone." 



Reduced from the plate in Hooke's Micrography, 1667. This 

 rock occurs in the Jurassic oolite, near Kettering, Northamp- 

 tonshire, England. 



FiGUBE 2. — Photomicrograph of sections of oolites from Great Salt Lake, Utah. 

 Nicols crossed. X 15. The large grain near the center has a 

 sanidine nucleus and shows the dark cross distinctly. The 

 two outer zones of this grain differ in texture from the gen- 

 eral mass of the grain. 



FiGUBE 3. — Great Salt Lake oolites. 



Reflected light. After Sherzer. 



FiGiJEE 4. — Section of Florida oolites from the Pleistocene. 



Nicols crossed. X 15. Many of the oolites have undergone a 

 partial recrystallization. 



FiGUBE 5. — Section of Cambrian oolites fi'om Waddle, Pennsylvania. 



X 15. Several of these ha^e recrystallized into calcite grains 

 showing twin lamellae. 



FiGUEE 6. — Another section of Cambrian oolites from Waddle. 



Nicols crossed. X 15. The dark crosses show that the radial 

 structure has been retained. 



