49Q 



REGINALD A. DALY 



A. Geikie has used "compound" in the sense of "composite" in the 

 foregoing definition; 1 Lawson has used "multiple" with the same 

 meaning. The nomenclature given in the above definitions is pre- 

 ferred, as it brings out the analogy with "multiple" and "composite" 

 sills and laccoliths — types already well named and established. 



A composite dike is illustrated in Fig. i . 



A dike network is a reticulate group of dikes simultaneously 



-H-l — I — I — I — i — I — I — I — I — I — I — I — I — I — I — I — I — 

 +++++++++++ +++++ + ■+-- 

 —I — f — i — i — l — I — f — l — i — l — I — f — f — I — I — I — f — l — 



— i — » — i — f — f— — < — ■ — i — i — *- 

 — f — ■ — i — i— —I — I — I — I — l — l— 



i±±±±±±±±±±, 



+++++++++++++++ 



-l — i — i — i — i — t — l — I — l — I — I — i — i — l — f — f — i — i — I — I — • — • — l — •- 



-H — | — I — I — t — (-H — I — i — I — f — I — I — I — 1 — "( — I — I — < — l"M"HH-+ 



+++++++++■+ + ++++ + + +++++;+■ 



Fig. 



injected. For illustration see Bulletin No. 2og, U. S. Geological 

 Survey, 1903, section, Plate 7. 

 Intrusive vein. 



I. J. B. Jukes: 2 



When the injected mass has arisen along an opened fissure, and solidified 

 there as a wall -like intrusion, it is called a dyke. When its path has been less- 

 regularly defined, and penetrates the surrounding rocks in a wavy thread-like- 

 fashion, this irregular protrusion is called a vein. 



II. A. Geikie: 3 



Veins have been injected into irregular branching cracks. 



1 Text-book, Vol. II, p. 746. 



2 Manual of Geology, edited by A. Geikie (1872), p. 263. 



3 Text-book (1903), p. 744. 



