The study area host primarily mudstone and shale with some outcrops
of pyrodastics. Small scale ironstone occurs within the shales as interbeds as
a result of oxidation.
Shale
The major and dorminant rocks
of the area are shales, outcropping throughout the entire region. The shales
are quite laterally and vertically extensive. The lithology of the shale varies
vertically with depth, the indurated shales are dark-greyish in colour and are
exposed in ditches, grains and river valley. They are also micaceous. The
fissile shales were exposed mainly at the stream channels. It contains lenses
of siltstones.
Pyroclastics
Evidence of igneous activity
in the study area occurs as pyrodastics. They are called the Abakaliki
pyrodastics. It occurs as an elongate and domical body in the study
area. These pyrodastics outcrops are dominant in the North and northwest parts
of the mapped area. They are exposed in areas like Juju hills, Ministry of Works
quarry and Sharon
mines.
Mudstone
In the study area, the
mudstones occur as the topmost sediment along side with reddish brown shale.
The colour ranges from brownish to milky yellow. The milky yellow erodes to
claystone. The reddish one on the other hand overlies the grayish and dark shales.
Unlike the reddish brown shales, the mudstones are blocky and lacks a clear
lamination as fissility.