Each valve was digitally imaged and x-y coordinates for fifteen landmark were recorded. congesta is common throughout the section and collected at 30-cm intervals over a three-meter high section. The different facies have different characteristic faunalĪssemblages, but M. The Rushmere is a coarse-grained shelly deposit, which grades into the much finer Morgart's Beach deposits, corresponding to a paleoenvironmental transition from higher to lower energy. The section is an unconformity-bounded sequence of thin shallow marine material deposited in less then 500 Ky. Mulinia congesta (Conrad), an opportunistic shallow infaunal siphonate suspension-feeding bivalve, was collectedįrom the Rushmere and Morgart's Beach Members of the Pliocene Yorktown Formation in southeastern Virginia. If paleoenvironmental conditions determine the morphology of a species then change will quantitatively affect morphology even at a fine resolution. Studies of invertebrate marine organisms have shown changes in shell morphology and size correlate with paleoenvironmental change.

Inkscape gradient bevels