Prof. F. Lcewinson-Lessing — Origin of the Igneous Rocks. 291 



Klernni 1 the diorite of the Odenwald originated through gabbro 

 assimilating scbists. Adams 2 speaks of limestones assimilated in the 

 contact zone by granites, and thinks that amphibolites have been 

 formed by this process. Michel-Levy, and with him Haug, 3 considers 

 the formation of granite as being accompanied by endogene meta- 

 morphism and assimilation on a large scale. I can cite also Philipp, 4 

 Termier, 5 Munteanu-Murgoci, 6 Cohen (on the laccolites of Piatigorsk), 

 Mackie, 7 Sauer, e Michel-Levy, 9 Lacroix, 10 Lemberg, 11 Doelter, 12 Giirich, 13 

 Hogbom, 14 Hugi, 15 Sollas, 16 Grenville Cole, 17 the ' osmatic ' theory of 

 Johnston-Lavis, and many other authors cited in my " Studien iiber 

 die Eruptivgesteine ". It is -well known that Sederholm 18 considers 

 assimilation as an important factor in the formation of the crystalline 

 schists. 



The above citations do not give a full account of all the advocates 

 of assimilation, but they are sufficient to show that many authors have 

 been led to this conception by various data and considerations. 



In different cases where a magma has come in contact with 

 surrounding rocks or with another magma assimilation must be an 

 important factor in differentiation. It is difficult to imagine a deep- 

 seated magmatic basin to remain in contact with eruptive or sedimentaiy 

 masses and not to dissolve a part of them, as fused silicates dissolve 

 a porcelain crucible. Those who deny this process on account of the 

 absence of zones of corrosion or of marginal zones due to admixture, 



1 G. Klemm, " Beobachtungen iiber die genetischen Beziehungen der Oden- 

 walder Gabbros und Diorite": Notizbl. Ver. Erdkunde Grosh. geol. Lande- 

 sanstalt Darmstadt (4), xxvii, 1906. 



a F. Adams, " On the Origin of the Amphibolites of the Laurentian Area of 

 Canada " : Jour. Geol., xvii, p. 7, 1909. 



3 E. Haug, Traite de Geologic 



4 H. Philipp, "Vorlaufige Mittheilungen iiber Resorptions- und Injections- 

 erscheinungen im siidl. Schwarzwald " : Centrbl. Min., 1907, p. 76. 



5 E. Termier, " Sur le granite alcalin du Filfla (Algerie) " : C.R., 1902. 



B Munteanu-Murgoci, Ueber die Einschlilsse von Granat-Vesuvicmfels in dem 

 Serpentin des Paringu-Massivs, 1901. 



7 Mackie, " On Differences in Chemical Composition between the Central and 

 the Marginal Zones of Granite Veins, with further evidence of exchanges 

 between such veins and contact rocks": Trans. Edinb. Geol. Soc, viii, 

 p. 98, 1901. 



8 A. Sauer, " Ueber petrographische Studien an den Lavabomben aus dem 

 Ries " : Jahresh. Ver. vaterl. Nat. Wfirttemb., lvii, 1901. 



9 A. Michel-Levy, Memoire sur le porphyre bleu de VEsterel, 1897. 



10 A. Lacroix, Guide des excursions, Congres de Paris, 1900. 



11 J. Lemberg, Z. d. g. G., 1872. 



12 C. Doelter, " Chemische Zusammensetzung u. Genesis der Monzoni- 

 Gesteine " : T.M.P.M., 1902, p. 206. 



13 Giirich, " Granit u. Gneiss " : Himmel u. Erde, xvii, p. 6, 1905. 



14 A. Hogbom, " Pre-Cambrian Geology of Sweden": Bull. Geol. Inst. 

 Upsala, x, 1910. 



10 Hugi, "Vorlaufige Mitteilung fiber Untersuchungen in der nordlichen 

 Gneiszone des zentralen Aarmassivs " : Eclogae Geol. Helvet., ix, No. 4, 1907. 



16 Sollas, Trans. Roy. Ir. Acad., xxx, p. 505, 1894. 



17 Grenville Cole, Sci. Trans. Roy. Dublin Soc. (2), vi, p. 246, 1897. The 

 last two authors are cited after Harker, Natural History of Igneous Rocks, p. 338. 



18 J. Sederholm, " Om Granit och Gneiss": Bull. Com. Geol. Finlande, 

 No. 3, 1907. 



