158 Ernest W. Skeats .■ 



along the coast southwards for H miles. Stretching inland from 

 the opposite or N.E. shores of Port Cygnet another outcrop of 

 alkali rocks occurs along the Peppermint Bay Road. One mile 

 N.E. of the town of Lovett are the alkali rocks of Livingstone Hill 

 The second group of alkali rocks occurring in the N.E. of the area 

 consists of the alkali porphyry of Woodbridge towards the northern 

 extremity of Peppermint Bay. Two outcrops occur here, intruding 

 the Permo-Carboniferous sediments. Permo-Carboniferous glacial 

 beds outcrop in Little Peppermint Bay. Further north, on the 

 south side of Little Oyster Cove, diabase, Permo-Caboniferous sedi- 

 ments and alkali porphyry are all represented. 



Between these two groups of outcrops in the S.W. and N.E. of 

 the area a gap of 8 or 9 miles occurs, consisting mostly of hilly 

 country, in which up to the present the only rocks known are diabase 

 and Permo-Carboniferous sediments. 



I visited all the localities mentioned above under Mr. Twelve- 

 trees' guidance, with the exception of the outcrop in Petchey's Bay, 

 which I have not seen. I am indebted to one of my students, Mr 

 E. 0. Cudmore, for specimens of the alkali rock from this 

 locality. 



Field Occurrence of the Alkali Rocks. 



In all the localities examined the alkali rocks present the charac- 

 ters of intrusive rocks. The petrographic descriptions by Mr. 

 Twelvetrees and by Professor Rosenbusch indicate that so far as 

 textural characters go some of the porphyries, with fine-grained 

 ground-mass, show fluidal and other characters, which occur in 

 lava flows, but since these textures are also represented in dyke 

 rocks and the field relations are generally clear, their intrusive 

 character 'is practically placed beyond question. Some of the 

 coarser-grained varieties near Regatta Point and the akerite mas» 

 on the back road from Lymington to Mt. Mary are described a& 

 syenites of various kinds, but they occur as relatively small intru- 

 sions, intimately associated with the smaller dykes, and are best 

 regarded as hypabyssal in origin, and described as larger dyke- 

 like masses. In every case except the one presently to be described 

 these rocks have penetrated the Lower Marine series of the Permo- 

 Carboniferous sediments. Junction specimens were obtained from 

 south of Regatta Point, and from Mt. Mary and at the latter place 

 especially the Permo-Carboniferous rocks near the contact are con- 

 siderably altered. They have been converted into indurated and 

 silicified rocks, more or less pyritized, and have been penetrated 



