010920c

Stylolite (jagged black line) is an irregular three-dimensional pressure-dissolution surface in limestone. This one separates silty peloid packstone (pink, upper right) from mostly dolomitized limestone (left and bottom). Impermeable stylolite prevented dolomitizing fluids from reaching the upper-right portion of this thin-section. Black material along the stylolite is insoluble residue of limestone that has dissolved away. Jurassic Smackover Formation, subsurface of Alabama. Thin-section photomicrograph, 2.5 mm wide.