Abstract: Microfacies ,and statistical study of the Shanty Falls reef, revealed that it consisted of three microfacies, ranging from bioconstructed limestone (extensions of the core) to biocalcarenite (tongue of the fore-reef) ,and dolosiltite (basin of the inter-reef). The microfacies study allowed subdivision in textural types and permitted differentiation and classification of the uniform limestone sequence. The data derived from microscope are used for correlation of eightfield sections, for tracing the evolution of the microfacies parameters, and for thebathymetry.The statistical measurements of the organic and inorganic parameters in thinsection disclosed that the reef system is cut through flank rocks by Wabash Riverand the core, which stays hidden to the south of the outcrop, is not yet exposed byerosion. The statistical consideration of the crinoids in the core extensions and inthe flank rocks showed that the fore-reef sequence is not altogether derived fromthe destruction of the main core, but growing in situ has received contributionsfrom the talus cones radiating from the central mound.This microscopic and statistical approach has brought in corrections and refinements to the older megascopic field observations.