BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 19, pp. 147-154, PLS. 9-10 JULY 6, 1908 



CONGLOMEEATE FORMED BY A MUvTERAL-LADEJs^ STREAM 



IN CALIFORXIA^ 



BY RALPH AHXOLD ASD KOBEET AN'DERSON' 



(Read hij title Jjcfore the Society Deceinhcr 31, 1901) 



CONTENTS 



Page 



Introduction and brief description 147 



Topograi)hy and geologj- 14(S 



Description of tlie deposits 148 



Origin and deposition of the cement , 350 



Topograpliic importance of the deposits 352 



Occurrences elsewhere 154 



IXTRODrCTIOX AXD BRIEF DESCRIPTIOISr 



I'hc purpose of this article is to describe a deposit of hard stream con- 

 glomerate that has been laid do-wn during the late Quaternary and is 

 still in process of formation in the valley of White creek, in the western 

 part of Fresno county, California. This stream is a branch of Los Gatos 

 creek, which flows southeastward from the Diablo range, the easternmost 

 member of the Coast ranges, and enters the San Joaquin valley at Coa- 

 linga. The deposit was observed by the writers in the summer of 1907, 

 during the progress of an investigation of the Coalinga oil district. 



"White creek flows from an area of serpentine and other metamorpMc 

 rocks and carries much mineral matter, which it deposits on evaporation 

 of the water. The gravel of the valley floor is thus cemented and is 

 changed to a solid pavement, through Avhich the stream subsequently 

 carves a channel, leaving the conglomerate as a terrace deposit along the 

 sides of the valley. The cement is largely calcium and magnesium car- 

 bonates, with minor amounts of silica and iron oxide ; the gravel is made 

 up of pebbles and boulders of many kinds of metamorphic and sedi- 

 mentary rocks, and the resulting conglomerate is so hard and compact 



"^ Published with the permission of the Director of the U. S. Geological Survey. 

 Manuscript received by the Secretary of the Society March 26, 1908. 



XV — Bum.. Geol. Soc. A.m., Vol. 19, 1907 (147) 



