172 Transactions. 



glauconitic sandstone." The glauconitic greensands (Lower Hutchinsonian) 

 are described in the following extracts : " The glauconitic sandy beds 

 at All Day Bay, Kakanui, Hutchinson's Quarry, and Grant's Creek are 

 loose and incoherent, but at the upper end of Target Gully, at Landon 

 Creek, and in the Waitaki area they form fairly compact glauconitic 

 sandstones " (p. 78). Further, it is stated that " the fauna of this 

 horizon [Lower Hutchinsonian] is distinguished by the abundance of 

 the brachiopod Pachymagas parki (Hutt.), by the presence of the corals 

 Isis dactyla Ten. -Woods and Mopsea hamiltoni (Thomson), and of the 

 cup-shaped bryozoan Celleporaria nummularia Busk. Besides these there 

 occur many pectens and other molluscs. Pachymagas parki (Hutt.) is 

 present almost everywhere, but the other fossils mentioned may be abundant 

 at one place and absent at another" (p. 78). " Pachymagas parki (Hutt.) 

 occurs in great abundance in the Lower Hutchinsonian, usually to the 

 exclusion of all other brachiopods except Rhizothyris rhizoida (Hutt.), 

 which is nearly always present with it" (p. 109). "The Lower Hutchin- 

 sonian is the most distinctive and persistent horizon of the Oamaruian 

 system ; it always overlies the Oamaru stone. In the Oamaru area it 

 consists of calcareous glauconitic greensands that at Landon Creek and the 

 lower Waitaki Valley are partly or wholly replaced by calcareous glau- 

 conitic sandstone. But whether greensands or glauconitic sandstone, the 

 characteristic brachiopod Pachymagas ])arki (Hutt.) and the peculiar 

 corals Isis dactyla Ten. -Woods and Mopsea hamiltoni (Thomson) are 

 always present. The Waitaki stone is underlain by the greensands " 

 (p. 110). 



It will be shown that these sandstone bands in the Landon Creek area 

 are referred to the Upper Hutchinsonian, although from Park's description 

 of the characteristic fossils they should belong to his Lower Hutchinsonian 

 (Hutchinsonian of Thomson). 



As pointed out by the present writer (1916, pp. 20-21), the fossil 

 Pachymagas parki (Hutt.) occurs in abundance in a well-defined band of 

 hard glauconitic sandstone. In the present paper this band is called the 

 " parki " band. It is ofter accompanied by Rhizothyris rhizoida (Hutt.), 

 to the exclusion of all other brachiopods. This hardened band is underlain 

 in many places in the district by looser greensands, also "glauconitic, but 

 characterized also by a constant assemblage of fossils — Aetheia gaulteri 

 (Morris), Terehratulina siiessi (Hutt.), Isis dactyla Ten. -Woods, and Mopsea 

 hamiltoni (Thomson), which are all very abundant. This bed usually con- 

 tains many specimens of Pachymagas parki (Hutt.), but in these looser 

 greensands the individuals of this species are on the average distinctly 

 smaller than in the upper " parki " band, and their external characters 

 are far more constant. In the hardened upper band, where it is usually 

 accompanied by Rhizothyris rhizoida (Hutt.), the specimens assigned to 

 the " parki " species are extremely variable in external shape. As 

 pointed out by Park in the extracts quoted above, this greensand horizon 

 is a most distinctive one ; it is the typical Hutchinsonian of the Oamaru 

 system, and always lies above a nodular band (Park's conglomerate). Park, 

 however, would term these " /sis " -greensands, and the '^ parki" green- 

 sands Lower Hutchinsonian ; and states that they are separated from 

 the Awamoan by the Upper Hutchinsonian (Waitaki stone). The writer 

 contends that the " Isis " greensands and the overlying " parki " green- 

 sands constitute the Hutchinsonian, and are followed directly by the 

 Awamoan beds. 



