Uttley. — Volcanic Rocks of Oamaru-. 109 



V. Descriptions of the Sections. 

 (1.) Oamaru Lighthouse. 



In the sea-cliff below the lighthouse near the Oamaru Breakwater a 

 good section is exposed (see fig. 1). 



The. tufaceous beds (a) are interstratified with limestone bands, which 

 often contain large subangular pieces of vesicular basalt. The bands 

 themselves vary up to 1 ft. in thickness, the lowest being 170 ft. below 

 the base of the lower pillow-lava. There is a marked discordance in the 

 dip of the tufaceous rocks below (a). These are not shown in the figure. 

 They dip 40° N. by E., while the dip of (a) is only 20° N. by E. It is 

 probably at this point that McKay introduces his unconformity between 

 his Cretaceo-Tertiary and Upper Eocene beds (1877, p. 58). From the 

 calcareous bands in the tuffs I collected the following forms : *Emarginula 

 wannonensis Harris, Siphonalia sp., Dentalium solidum Hutt., *Pecten 

 hutchinsoni Hutt., Sip/ionium planatum Suter, Liothyrella oamarutica 

 (Boehm), L. boehmi Thomson, Terebratulina suessi (Hutt.), Aetheia gualteri 

 (Morris), and Hemithyris sp. 



The overlying pillow-lava is at a minimum estimate 100 ft. thick. The 

 interspaces are filled with fossiliferous limestone, much hardened in places 

 by a secondary deposit of calcite, and the fossils are difficult to extract 

 A detailed description of this peculiar rock and others similar to it will be 

 given later. The following fossils were obtained from the interstitial lime- 

 stone : *Trochus sp., *Turritella sp., *Polinices huttoni von Ihering, *Lima 

 bullata Born, *Lima lima (L.), Ostrea sp., and Hemithyris sp. 



d, e f q 



jr IG . i. — Section near lighthouse, Oamaru. (a) Tuffs with limestone bands ; 

 (b) lower pillow-lava ; (c) fine tuffs (current-bedded) ; (rl) tuff- 

 bed (very calcareous) ; (e) limestone band with rounded and 

 subangular pieces of volcanic rock ; (/) blue tufaceous clay ; 

 (g) limestone ; (h) tufaceous limestone ; (j) raised beach ; 

 (k) broken pillow-lava. 



The tuff-beds (c) are very fine and current-bedded, but unfossiliferous. 

 The overlying tuffs (d) are very calcareous and coarser in texture. I col- 

 lected the following forms : Epitonium lyratum (Zitt.), Lima Jeffrey siana 

 Tate, Ostrea sp., Venericardia purpurata (Desh.), and Diplodonta zelandica 

 Gray. 



The limestone band (e) is crowded with subangular pieces of volcanic 

 rocks, while small pieces of augite were also identified. Bed (g) is a much 

 purer limestone than bed (h), which is very tufaceous. 



In the limestone (g) the following forms occurred : Epitonium lyratum 

 (Zitt.), *Pecten hutchinsoni Hutt., *P. delicatulus Hutt., Terebratulina suessi 

 (Hutt.), *Liothyrella boehmi Thomson (?), and *L. oamarutica Boehm. 



The overlying tufaceous limestone (h) is also fossiliferous, and the 

 following species were identified : *Limopsis aurita Brocchi, Pecten deli- 

 catulus Hutt., *Lima jeffreysiana Tate, Ostrea sp., ^Venericardia purpurata 

 (Desh.), V. zelandica (Desh.), Protocardia pulchella (Gray), .and Terebratulina 

 suessi (Hutt.). 



