42 WARREN D. SMITH 
structural line. This river is navigable up to Ilagan, and along its 
banks are located the principal tobacco fields of the Islands. At 
Aparri considerable difficulty is experienced from the formation of 
bars crossing the river mouth. The insular government is spend- 
ing considerable money in keeping this channel open. This stream 
flows in a very wide, level plain and the soil is remarkably rich. 
The Pampanga.—The second largest river of Luzon is the 
Pampanga. This river rises in the Caraballo Sur Mountains or in 
the ‘Central Knot,” and flows somewhat west of south and 
debouches into Manila Bay, by means of a myriad of channels. 
This river is navigable for a long distance into the interior, and is 
one of the principal highways of commerce in Luzon. 
The Agno.—The Agno river rises on the slopes of Mount Data 
in north.central Luzon, and flows due south until it reaches the 
Pangasinan Plain where it turns sharply to the northwest and 
empties into Lingayen Gulf. , This river is navigable for a short 
distance from its mouth, but in the mountain district is simply a 
roaring torrent washing along big bowlders, and is not at all naviga- 
ble. This river overflowed its banks twice during ee flooding 
a large section of Pangasinan Province. 
The Abra.—The Abra rises also on the slopes of Mount Data, 
then turns abruptly to the north, flowing for 40 miles or more until 
it gets to the town of Dolores, where it makes another very sharp 
bend and flows southwest, emptying into the ocean near Vigan. 
This river throughout a great deal of its extent is located in a deep 
gorge. Very little is known of the geology along its course. 
The Bicol River.—The Bicol River where it rises due west of 
Daraga is known as the Kinali River. Thence it flows northwest 
along the Albay central plain, through one lake (Lake Bato) and a 
large swamp, finally emptying into San Miguel Bay. This river is 
navigable almost to Bato Lake. It very frequently overflows, and 
for this reason, the district through which it flows is one of the 
principal rice districts of the Islands. 
The Angat River —The Angat River is referred to here more on 
account of its length, than for any other reason. It rises in the 
Eastern Cordillera, flowing with considerable sinuosity westward, 
and empties into the Kingwa River which also flows across the 
