| Abstract/Notes | My attention was first drawn to this subject by the study of a remarkable crystal breccia, occurring at Kakanui, New Zealand, of which a description is given below. The only similar phenomena I could read of in the Colonial libraries at my disposal were those of the diamond pipes at Kimberley, described by Professors Carvill-Lewis, T. G. Bonney, and Miss Kaisin in this Magazine.2 Having since had the opportunity, thanks to the hospitality of Professor Lacroix, of studying in his laboratory at Paris, I found that the proper discussion of this subject comes under the study of the inclusions of volcanic rocks, of which he has given so admirable an account in his book “Les Enclaves des Roches volcaniques.”3 At his recommendation I collected some inclusions from the well-known dolerite of Portrush, and studied them under his guidance. The present paper consists of a discussion of rocks from these two localities, with descriptive notes on a few other inclusions that I have in my collection.Two things stand out clearly from a cursoiy examination of this book, the frequency, almost the universality, of inclusions in igneous rocks, and the importance of the aid which they afford to the student of volcanic phenomena. Under these circumstances, it is remarkable how long this branch of study has escaped attention from. British geologists. Lacroix's useful nomenclature has not been adopted in our literature, although Phillips, Teall, Sollas, Harker, Judd,1 and others have paid considerable attention to some varieties of inclusion, and Harker has established a slightly different classificationof these phenomena. |
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