GEOLOGIC IJECOXNAISSAXOE OF MINDANAO AND SULU. 489 



which the species are for the most part identical with those growing in 

 the sea below, hut within about 300 meters the road cuts through basalt, 

 and continues in this formation until Malabang on the southwest coast 

 of this portion of the island is reached. Maria Christina Falls are 

 situated but a short distance ofE the main road, a few kilometers out from 

 Overton. Here the swift waters of the Agus Eiver, which drains Lake 

 Lanao, fall over a cliff 58 meters high and continue to the sea through 

 a narrow gorge. 



It has been estimated that sufficient power can be developed by these falls by 

 means of turbines to run electric freight and passenger trains from Camp Overton 

 to Camp Keithlej' and then around the lake and down to JIalabang. Furthermor*^; 

 the power from this and the Mataling Falls together should also be able to furnish 

 electric light for a dozen towns and camps along this route. 



The rock in the upper portion of the section at the waterfall is a hard, 

 rather structureless basalt ; below this comes a more or less loose volcanic 

 conglomerate, or better, agglomerate, the geologic structure giving the 

 luost favorable conditions for fall formation. Maria Christina has about 

 the same height and volume of water as the better known Majayjay Falls 

 of Luzon, 



The road, ver}'' soon after the fork to the waterfall, leaves the rather 

 heavy timber. From here on it ascends a long, gradually sloping, quite 

 open and rolling plain, resembling the western prairie of the United 

 States. 



The Agus flows in a broad valley with gently sloping sides at Numun- 

 gan and while at this point it has a fairly rapid current, it gives no 

 intimation whatever of the terrible plunge a few miles farther on. A 

 party of engineers is stationed at Pantar some distance beyond this point 

 to look after the roads and bridges, and we spent two days here to 

 examine the cuts along the road and river bank. Basalt is still the 

 country rock here, but it has on top an extraordinarily thick mantle of 

 weathered material full of basalt bowlders, and both in constitution and 

 topography this simulates glacial morainal material. 



From Pantar the road runs fairly straight for seven to nine kilometers 

 across open rolling country to the "Keithley escarpment." Beyond this- 

 escarpment lies Lake Lanao. The road continues almost due south to 

 the foot of this great wall, then turns practically due east and, keeping 

 nearly parallel with it, climbs gradually to the top. Prom here it runs 

 down a long, easy grade to the margin of the lake. 



This escarpment is very striking, and is made up from top to Ijottom, 

 as far as can be seen from its cuts in the road, of loose material, unsorted 

 and with apparently no definite structure, forming a wall 155 meters 

 high. A simple explanation of this phenomenon is not easy to find. 



To the left, when facing toward Camp Keithley from the top of the 

 embankment, rises the dark, heavily wooded mass of "Sacred Mountain" 



