HuTTON. — Geology of Sorth-eastern Otago. 419 



sandstones with fossils, and then the Otatara limestone, 45 

 feet thick. The details of this part of tlie section I will defer 

 until treating of the Hutchinson's Quarry beds. 



It will be seen that the beds all round the east side of the 

 Oamara Peninsula form a single periclinal curve, as shown by 

 me in 1875.* Mr. McKay's section! is very different, and I am 

 at a loss to account for it, as he gives no details. 



2. Deborah Volcano. — Between the Deborah railway-station 

 and Totara are the relics of another volcano, which has been 

 almost entirely destroyed by denudation. The rocks are basic, 

 but I neglected to collect specimens. So far as I could see, they 

 always underlie the Ototara limestone, which surrounds the 

 volcano on all sides but the south-east. Mr. McKay, however, 

 mentions a lava flow overlying the limestone somewhere in the 

 neighbourhood.! He gives no precise locality, and I failed to 

 find it ; but as I arrived late in the day I could not make a 

 sufficiently careful examination. In the Waireka Valley, opposite 

 Deborah, a tachylyte tuff, probably erupted from this volcano, 

 underlies the Ototara limestone, but I will give its position when 

 describmg the sedimentary rocks of the Ototara series. This 

 tufl' is compact, grey in colour, and with a lens shows minute 

 black shining spots, and occasionally small pieces of vesicular 

 tachylyte. It effervesces freely with acid, S.Gr.=2-47. Under 

 the microscope it is seen to be made up of minute angular 

 fragments of vesicular tachylyte in a calcareous cement. The 

 tachylyte is of a pale yellow-brown colour, without any felspars, 

 but contains a few scattered microliths. The vesicles are 

 ovoid, not much elongated. It is much like a tachylyte tuff, 

 presently to be described, from Lookout Bluff. 



3. Enfield Volcano. — The railway at Enfield runs through an 

 old volcano which extends as far as Elderslie (Section III.). It 

 is formed principally by lava flows, which are compact and finely 

 crystalline. Some are dark grey in colour, with small white 

 pearly flecks, and cavities filled with limonite; these rocks 

 weather reddish-grey. Others are darker, and without white 

 flecks. S.G.= 2-64. I could see no olivine in any of them. 

 Under the microscope these rocks are seen to have a micro- 

 crystalline ground-mass of felspar laths, brownish augite grains 

 and ilmenite, more or less decomposed into leuxocene. There 

 are no porphyritic crystals. In the absence of chemical analysis, 

 I feel inclined to call these rocks augite andesites. At the road 

 cutting close to the Waireka Presbyterian Church, there is a 

 palagonite tuff composed of fragments of tachylyte and fragments 

 of black magma-basalt with olivine. S.G.=:2'35. The tachy- 

 lyte is altered in places into a yellow-brown or brownish-green 



* " Geology of Otago," p. 55, fig. 7. 



t "Rep. Geol. Expl.," 1876-77, p. 50, section No. 3. 



+ " Eep. Geol. Expl.," 1876-77, p. 58. 



