360 SMITH. 



Terraces originate in several ways and according to their origin we 

 discriminate the following: 



River terraces J L Flood-plain terraces. 



12. Those due to inequalities of hardness of strata. 



Marine terraces.... L Wave built " 

 12. Wave cut. 



Lake terraces The same as marine. Usually on a smaller scale. 



I have already alluded to the terraces of the Cotabato Valley. These 

 are in part marine wave cut, in part river cut, and also due to the eleva- 

 tion of reefs. However, the most striking terraces are those along the 

 present seashore. Exceptional examples are to be seen. At Point 

 Blanca, on the northwest coast of Mindanao, there is a raised delta of 

 an old river. It is sliced off at the sea margin so that the structure is 

 clearly revealed. A sea cliff exists in this soft material of from 6 to 9 

 meters elevation (estimated from the boat) . Formerly, the lower end of 

 this delta was at the level of the sea. The structure as now apparent is 

 that of a typical delta with the cross-bedding always found in such forma- 

 tions. 



The second striking example is to be seen in Makajalar Bay. Here 

 the terracing is very pronounced. I am indebted to Miss Eleanor P. 

 Bliss for the following sketch made on a visit to this locality in 1907. 

 (See fig. 5.) 



The meaning of these terraces, raised deltas, and beaches is that 

 Mindanao, in some quarters at least, is rising. Very accurate coast and 

 geodetic work, such as is being carried on now, and a comparison of the 

 present with a resurvey fifty or a hundred years hence, might reveal a 

 measurable increase in area. 



STJLU. 



In the Sulu Archipelago vulcanism has played a most prominent 

 part and for the most part is of more recent date than that of Mindanao. 



On the Island of Basilan there are many extinct cones and more on 

 Jolo, accompanied by many hot springs. On Tawi Tawi the signs of 

 recent vulcanism are not so pronounced, and as far as I know this island 

 is largely made up of sedimentaries. Siasi is practically a partially 

 worn-down volcanic stock. In all these islands we have no distinct 

 cordilleras, but numbers of more or less isolated cones which do not 

 appear even to have linear arrangement, although a more detailed survey 

 might reveal some such system. Subsequent erosion has produced in 

 these islands a topography which is peculiar and very pleasing in its 

 long, gentle slopes and beautiful curves. Jolo is only partially wooded, 

 there being long stretches of fields covered with waving cogon with here 

 and there cleared patches on which the industrious Moro has cultivated 

 the tapioca plant with its striking pink blossom. The soil is deep, rich, 

 red, and exceptionally fertile, and would be excellent for sugar. 



