220 Wisconsin Academy of Sciences, Arts, and Letters. 
The water has a bluish-green color and is much more trans¬ 
parent than that of lake Amatitlan. In 1906 Meek 1 found that 
a white disc 30 cm. in diameter could be seen at a depth of 
13.7 m. On February 15, 1910, a disc 10 cm. in diameter dis¬ 
appeared from view at a depth of 10 m. Meek found a maxi¬ 
mum depth of 322 m. and a rather large portion of the lake, ap¬ 
parently, has a depth of 300 m. or more. 
Owing to the narrowness of the marginal shelf and the steep 
slope of the bottom, the larger aquatic plants are rather scarce 
along the shore, not being able to gain a foothold in most places. 
They are found more frequently along the deltas of the small 
affluents and consist of such forms as Typha, Scirpus, Potamo- 
geton, and Ckara. 
LAKE ILOPANGO. 
Lake Ilopango lies in a picturesque valley about 10 km. south¬ 
east of the city of San Salvador, the capital of the republic of 
Salvador. It lies jn 89° west longitude and 13° 42' north lati¬ 
tude. The surface of the lake is about 490 m. above sea level. 
The longest axis of the lake lies in an east-west direction and is 
about 9.2 km. in extent; the maximum width is about 7.3 km.; 
and the area is 54.3 sq. km. (See fig. 3, p. 221.) The basin oc¬ 
cupied by the lake appears to have had a volcanic origin, prob¬ 
ably the coalescence of several points of eruption. 2 The region 
is still subject to seismic disturbances which have affected the 
level of the lake at various times. 
Brigham states that most of the small towns in the neighbor¬ 
hood of Lago de Ilopango were destroyed by earthquakes on De¬ 
cember 27 and 30, 1879. On January 11, 1880, the water of the 
lake had risen more than a meter and it is estimated that on the 
following day nearly 14,000,000 cu. m. of water were discharged 
through the outlet of the lake, making a stream of greater volume 
than the Seine at Paris. On January 20, 1880, about 11 p. m., a 
great disturbance was noted near the middle of the lake and the 
next morning a pile of rocks was seen from whose midst arose a 
column of vapor. These rocks now constitute two small islands 
near the middle of the lake. The larger island is 90 m. to 100 m. 
long and 20 m. to 30 m. wide and rises from 8 m. to 10 rn. above 
1 Log. cit, p. 180. 
2 Brigham. Guatemala, the Land of the Quetzal, p. 402. N. Y., 1887. 
