Te Kuiti group in the Waitomo-Te Anga area

It is proposed to divide the Te Kuiti Group, a transgressional sequence of shallow-water, dominantly marine beds of Oligocene age, into two subgroups. The lower Te Anga Subgroup is mostly calcareous siltstone and sandstone, and includes the Aotea Sandstone, Whaingaroa Siltstone, and thin basal conglomerates, sandstones, and limestones; the overlying Castle Craig Subgroup, dominantly f1aggy shell limestone, includes the Orahiri Limestone, Waitomo Sandstone, and Otorohanga Limestone, all of which grade into one limestone unit of comparable thickness south and west of Waitomo. The boundary between the two subgroups is defined as the pebbly horizon at the base of the main flaggy limestone sequence. Thin conglomerates, sandstones, and limestones were deposited on a gently undulating erosion surface. Transgression of the sea from the north formed an embayment at least 30 miles wide in which dominantly fine grained sediments were deposited below wave base. Relatively strong currents near the centre of t...