ABSTRACT
The connecting channels into the Nashua Lagoon system allowed Waccamaw-type cooler water conditions, sediments, and ecosystems to exist at the northern end of the Kissimmee embayment. The clay component of the unconsolidated beds increases in abundance in the northern extent of the formation. In the southern areas of Nashua deposition, the dark gray sandy limestones often occur in thick, massive units and are mined commercially for road construction. The same massive gray arenaceous sparite-limy sandstone of the Fort drum member is also exposed within the Indrio Pit west of fort pierce, but there it lacks the Mercenaria geodes. In the Indrio pit, the unconsolidated beds below the gray sandy limestone are not filled with Mercenaria clams but, instead, are replaced by beds of beautifully preserved busyconid whelks (several genera and species). The percentages of clay minerals increase in the northern part of the member, whereas the carbonate fines dominate in the southern part.
