UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 7, No. 2, pp. 21-38, pis. 3-6 Issued May 25, 1912 



PSEUDOSTRATIFICATION IN SANTA 

 BARBARA COUNTY, CALIFORNIA 



BY 



GEORGE DAVIS LOUDERBACK 



CONTENTS page 



Stratification, its meaning anil origin 21 



Pseudostratification 22 



Territory studied 23 



General nature of the formations involved 23 



Occurrence and appearance of exposures 24 



Determination of original structures .. 24 



Subordinate secondary layers 25 



Pseudofolds 25 



Cement of indurated layers 26 



Sand pendants 27 



Explanation of phenomena 28 



Necessary conditions for production of observed phenomena 29 



Discussion of origin of subordinate layers 30 



Stratification, its meaning and origin. — Stratification as ap- 

 plied in structural geology to rock formations may be defined as 

 an arrangement in layers or "beds" as a result of the processes 

 of sedimentation or of the extravasation of sheets of lava. 1 



i There is some difference of usage here, and many geologists do not 

 include the bedded lavas as stratified formations. Their common occur- 

 rence in beds; their formation of series either alone or with their inter- 

 bedded tuffs, or interstratified in the sedimentary series; the fact that their 

 bedded form is due to the same fundamental conditions as for sedimentary 

 strata (surface conditions, gravity and a pre-existing floor) ; the possibility 

 of using their attitudes and deformations in exactly the same way as 

 those of sedimentary beds for determining structural relations and earth 

 movements, mark them fundamentally as stratified in the same sense in 

 which the sediments are. 



The usage common in geological text-books of making a sharp distinc- 

 tion between stratified or sedimentary and massive or igneous rocks with- 

 out further qualification or comment ignores some very important relation- 

 ships. Surface igneous rocks are not only commonly stratified, but often 

 also sedimentary. The volcanic tuffs frequently form stratified sedi- 

 mentary formations of great thickness and areal extent, as for example in 

 the Mesozoic and Tertiary areas of many of the western states. 



