Calcareous glades are those that are associated with exposures of limestone or dolomite bedrock. They occur in each of the three grand divisions of Tennessee but are most abundant in Middle Tennessee. Dolomite glades are very rare and restricted to extreme northeast Tennessee near the Virginia line.
Limestone glades are most abundant in the Nashville Basin where they occur in the broad basin bottom or on benches of low hills. NatureServe (2015) classifies these glades as part of the Nashville Basin Limestone Glade and Woodland ecological system. The southern Ridge and Valley also supports many limestone glade areas and dolomite glades are restricted to a couple of very small areas in extreme northeast Tennessee's Ridge and Valley near the Virginia state line. These calcareous glades of the Ridge and Valley are grouped by NatureServe (2015) into the Southern Ridge and Valley Calcareous Glade and Woodland ecological system. Small limestone glades associated with usually sloping limestone barrens and woodlands are also found along the Tennessee River (Decatur, Hardin, Perry, Wayne counties) and along the escarpment of the Cumberland Plateau. These glades are mostly tiny inclusions within limestone barrens or woodlands. NatureServe groups these within the Central Interior Highlands Calcareous Glade and Barrens ecological system.
NatureServe (2015) also recognizes the Southern and Central Appalachian Mafic Glade and Barrens ecological system as occurring in Tennessee. Mafic rocks are those with high base (e.g. calcium, mangesium) content except the term generally refers to igneous or metamorphic rocks (e.g. amphibolite, gabbro, gneiss). In this classification, mafic glades are not recognized as occurring in Tennessee but rather they are recognized under Outcrops.
EAST GULF COASTAL PLAINS
WESTERN HIGHLAND RIM ECOREGION
NASHVILLE BASIN ECOREGION
EASTERN HIGHLAND RIM ECOREGION
CUMBERLAND PLATEAU ESCARPMENT ECOREGION
Cumberland Plateau Escarpment Limestone Glade
SEQUATCHIE VALLEY ECOREGION
Sequatchie Valley Limestone Glade