Savigné-sur-Lathan, Indre-et-Loire, France

   This is fossiliferous sand made up of fragments of bryozoan colonies, a small snail (Turitella?) and some quartz grains. These sediments
record marine life along a shallow continental shelf that bordered the Atlantic Ocean in western France about 15 million years ago. To scientists, the absence of coral or algae in this sample is indicative of cool marine water and changing tidal conditions.

   Bryozoans are common in the fossil record and are abundant in oceans today. They have calcareous skeletons and range in size from a few millimeters to large branching growths of several meters in height.

   Savigné-sur-Lathan is located southwest of Paris in the Loire Valley. Since the 17th century, farmers have quarried and used the calcium
carbonate deposits to enrich their farmlands; only a few deposits remain today.

David Monniaux  CC-BY-SA-3.0