dissected Location Geological formation Nanka Sandstones of sedimentary origin Awkuzu Sandstones of sedimentary origin Okigwe Sandstones of sedimentary origin Nkpologu False bedded Sandstones (Ajali Formation) Abakaliki Asu River Group (shale) Enugu Awgu/Ndeabo shale Ugwuoba Imo Clay shale
Yahe Ezeaku shale Ogoja I Ezeaku shale Ogoja II Ezeaku shale Table 2.
Nichols (1980) reviewed the literature concerning valley-floor expansion in terrains composed of clay, clay shale
, and shales interbedded with limestones and dolomites.
The classification is as follows: shale is called "black shale" when sapropel content is less than 5% ; and it is known as clay shale
with rot when sapropel component content is between 5 ~ 25%; when sapropel content is between 25 ~ 50%, we call it rot muddy shale/sapropelic shale.
This volume also contains the 33 keynote presentations on recent advances in geotechnics, covering such topics as developments in understanding soil behavior, ground performance and building response due to tunneling, comparative study between liquefaction and instability of sand, inherent anisotropic stiffness of decomposed tuff and alluvium, and mechanical behavior of highly fissured sheared clay shales
, to cite a few.
Although the quartz content of clay shales
of the Dividal Group is slightly higher (secondary silicification?