50 Grandall — Santa Clara Valley Region in California. 



thousand feet ; bat in the thickest known section of Creta- 

 ceous on Elder Creek the Chico is only four thousand feet ; and 

 south of Mt. Diablo at Arroyo del Yalle four thousand feet is 

 the thickness of combined Horsetown and Chico, with the same 

 amount for Knoxville. Thus, at Mt. Diablo, the six thousand 

 feet must represent more than the Chico and some of it may 

 be considered Horsetown. The series seems to be conformable 

 and sedimentation was probably slower at this place than in 

 northern California. 



South of Arroyo del Yalle, the Horsetown has not been rec- 

 ognized * and the Chico is found resting- unconformably upon 

 Knoxville shales and sandstones, into which serpentine has been 

 intruded in pre-Chico times. 



II. and III Sections at Arroyo del Vane. 



N2I° W 



IV. Section at Mt . Diabio. 

 O 



V. Section across the Santa Lucia. Range. 

 Scale unknown. 



legend . 

 T.- TERTIARY. 

 C- CHICO. 

 H.- HORSETOWN. 

 K.- KNOXVILLE. 

 F.- FRAJ1CISCAM. 



Comparative sections showing the relations of the Cretaceous in California. 



Cause of Absence of Horsetown in Southern California. — 

 The lack of Horsetown in Southern California shows that at 



* A specimen of Hoplites Remondi has been picked np in the hills near 

 Del Monte, but nothing definite is known about its occurrence. 



