18 



Physiography 



Figure 16. Cretaceous sand- 

 stone from Whale View Point, 

 La Jolla, showing broad inden- 

 tations made by biochemical 

 activities and perhaps mechan- 

 ical rasping of small snails — 

 Littorina. Limpets lower in the 

 photograph often make holes 

 like those of chitens, but these 

 particular ones have not done 

 so. Photographed January 

 1944. 



Figure 17. Solution basin in 

 Cretaceous sandstone at Whale 

 View Point, La Jolla. Basin is 

 nearly fiat-floored but has steep 

 sides that are fluted. Small 

 snails, Littorina, cluster in flut- 

 ings. Algae present on the 

 floor during winter are absent 

 during summer. Biochemical 

 studies show that solution of 

 calcium carbonate cement oc- 

 curs at night and deposition of 

 calcium carbonate, mostly re- 

 inforcing rims, during the day- 

 time. Photographed January 

 1944. Re-examination in Au- 

 gust 1956 showed negligible 

 change. From Emery (1946, 

 Fig. 5). 



Figure 1 8. Solution basins in 

 Miocene basalt near Resort 

 Point, Palos Verdes Hills. Ba- 

 sins are believed to form by 

 biochemical methods like those 

 in sandstone and limestone. 

 Photographed May 1956. 



