051821

 

More pictures of the Mississippian microbial reef in North Alabama.  

 

A busy part of the reef, consisting of microbial thrombolitr (originally nonlaminated lime mud, which is commonly clotted or pelletal). B=fragment of a bryozoan, A="Problematicum A," a tubular fossil, S=a cement-filled shelter void (note semicircular single-chambered foraminiferan on the roof, left of "S"), lower arrow=multiple microfossils encrusting the bryozoan, left arrow=more on the top side, upper left arrow=a former void now filled with miscellaneous very fine particles (there's another on the lower right). Scale 0.5 millimeters. The reef grew in shallow warm marine water close to the shoreline, perhaps in a lagoon.