270 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 13 



From both peaks the land falls abruptly to the water's edge in nearly 

 vertical cliffs. The extension of these cliffs forms the northern and 

 southern boundaries of the two main terraces. The eastern face of the 

 island presents an alternating series of abrupt cliffs and moderately 

 sloping bluffs. Detached segments of the main ridge form small islets 

 to the north and south of the island. 



There are a few narrow sand beaches in shallow coves on the south- 

 ern and northwestern coast but as precipitous cliffs encircle these coves 

 the only practicable landing places are on the lee side of projecting 

 rocky ridges. The heavy surge from the south makes landing precarious 

 at best and impossible at times. There is good anchorage in most weather 

 off the eastern coast. 



The rocky foundation of the island is volcanic in nature, consisting 

 mostly of alternating beds of indurated breccias and tuffs. One very 

 small sedimentary deposit, apparently of Pleistocene age, is located at 

 an approximate elevation of 148 meters (475 feet) near the southern 

 end of the island. Six shallow canyons cut directly across the lower 

 part of the eastern terrace. Only one of these. Graveyard Canyon, has 

 developed a steep-walled gorge. Except for a small seepage on one of 

 the eastern bluffs there is no permanent water on the island. 



The wide marine terraces of the island and the abi-upt cliffs rising 

 almost directly from the water play such an important role in the de- 

 velopment of plant communities that it may be well to consider the 

 origin of these features. Santa Barbara Island, in common with the 

 other islands, with the possible exception of Santa Catalina, appears 

 to have undergone considerable elevation in no very remote geological 

 time. This is inferred from the presence of marine terraces. San Cle- 

 mente Island has seventeen terraces, rising to a total height of 400 

 meters (1320 feet) (Lawson, 1893). These indicate intermittent periods 

 of uplift. Santa Barbara, owing to its lower elevation, has only two 

 levels of terraces. The Pleistocene deposits at a higher level than the 

 terraces might indicate greater uplift than that shown by the terraces, 

 but the sharp angles on the rocks of the highest ridge do not indicate 

 that the island was completely submerged prior to the uplift. The 

 depth of the canyons on San Clemente would place the major period of 

 uplift well back into the Pleistocene, and the small amount of surface 

 erosion on the terraces of San Clemente, San Nicolas, and Santa Barbara 

 would indicate no longer lapse of time. 



The formidable cliffs and bluffs surrounding the island are due to 

 the ceaseless attack of the sea upon the shore line. This is undoubtedly 

 the most powerful geological agency operating upon the island during 



