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Ooid grainstone, a high-energy tropical shallow-water sand in which interparticle pores have been entirely filled with cement. Jurassic Smackover Formation, subsurface of South Alabama, thin-section photomicrograph, stained with Alizarin Red S, which stains calcite pink, blue areas are open pores filled with blue epoxy in this thin section preparation.

Geology photo

Meniscus cement, ooid grainstone, Monteagle Limestone, Mississippian (lower Carboniferous), north Alabama. Photo by Doug Haywick.

Doug and I are working together on a study of carbonate mounds, but when we came across this beautiful example of meniscus cement, we both knew we had to photograph it.

Foundation of a Mississippian carbonate mound

Thin section photomicrograph (image 2.5 mm wide), part of an ancient carbonate sand shoal. Later, a small mound grew on top of the shoal. Ooid grainstone.