Laterally extensive layers (tens to hundreds of metres wide) are made up of interlaminated
siliciclastic mudstone and sandstone, displaying lenticular, wavy, and flaser stratification, and ubiquitous desiccation mudcracks and vertebrate footprints.
In detail, the foliation is defined with the preferentially arranged crystals of phylosilicates, planar aggregates of re-crystallized quartz; in the case of migmatized gneisses, with the interlaminated
stripes of mezosomes and leucosome.
They are commonly massive-bedded, blocky and splintery, though in places are interlaminated
with thin, red, maroon, dark grey and dark green siltstone layers to form shales.
The lignitic interval in Kemper County is approximately 165 feet thick, includes interbedded to interlaminated
sand, silt, and clay, and is positioned largely within the Tuscahoma Formation.
Downstream, a tall bluff (Locality 8), about 20 m in height, is exposed directly on the right bank of the river, and can be recognized from Penrose's (1889) description (although the distance he reported is about twice the actual): "One half mile below this [McDonald's Bluff] and on the same side of the river is a ledge about 50 ft high of chocolate clays and sands and also gray sands, interbedded and interlaminated
, also beds of semi-indurated greensand".
Argillaceous and calcareous sandstones and siltstones of the Chaleurs Group and limestones interlaminated
with calcareous shales of the Matapedia Group underlie most of the western part of the study area (Fig.
Above the maestro layer are marls (to 2 meters) followed by gypsum layers (1-2 meters) interlaminated
with thin marl horizons.