2 CALIFORNIA ACADEMY OF SCIENCES. [PROC. 30 SER. 



PAGE. 



5. RELATIVE AGE 41 



B. TUFF AND DIATOMACEOUS EARTH 42 



1. OCCURRENCE 42 



2. TUFF 43 



3. SHALE 43 



Microscopic Characters 44 



Character of the Organic Remains 45 



Chemical Characters 48 



Origin of the Shale 49 



Analysis of Limestone 50 



C. SEDIMENTARY DEPOSITS 51 



D. BRECCIA 52 



E. BASEMENT SERIES 54 



1. QUARTZITE 54 



Macroscopic Characters 55 



Microscopic Characters 57 



2. ACTINOLITE AND HORNBLENDE SCHISTS 58 



3. SERPENTINE 58 



4. TALC-SCHIST 60 



5. ORIGIN OF THE SERPENTINES 61 



6. GARNET- AMPHIBOLITE 62 



IV. GEOMORPHOGENY 65 



1. SUBMARINE TOPOGRAPHY 65 



2. OUTLINE OF HISTORY 67 



I. INTRODUCTION. 



i . LITERATURE. 



THE existing literature bearing upon the geology of Santa 

 Catalina is very limited, consisting of a short note in Whit- 

 ney's Geology, 1 a brief report 2 and other scattered notes in 

 the various Annual Reports of the State Mining Bureau, 

 and a recent account of the topography of the island, by 

 Prof. Lawson. 3 The report of the State Mining Bureau 

 is not only superficial, but very inaccurate. In Whitney's 

 report the absence of terraces is noted, contrasting with the 

 neighboring islands, and the suggestion is made that this 

 island may be sinking. Both of these points are elaborated 



1 Geol. Surv. of Cal., Geol., Vol. I, pp. 182-186. 

 2 Tenth An. Rept., State Mineralogist, pp. 277-281. 



8 "The Post-Pliocene Diastrophism of the Coast of Southern California," by Andrew 

 C. Lawson. Bull. Dept. Geol., Univ. Cal., Vol. I, No. 4, pp. 135-139' 



