AGASSIZ: THE FLORIDA ELEVATED REEF. 53 
locality the rise is gradual, commonly from a coastal swamp (Plate XX.). 
Inside of Key Largo the coastal swamp is ten or twelve miles wide. 
The oólite rises to an elevation of about twenty feet, and then main- 
tains a generally level surface, with the exceptions of occasional broad 
undulations, having axes about east to west or north to south, and sinks. 
The hollows of the broad undulations are filled with water during the 
rainy season, so that pines do not grow in them; in the dry season grass 
grows luxuriantly, and some of the sinks are cultivated. Some soil has 
accumulated in these “ prairies," whereas among the pines there is 
scarcely any soil to hide the jagged rock surface and loose fragments 
(Plate XXI. Fig. 2). The sinks are sometimes of rounded form, with 
perhaps a maximum diameter of two hundred feet, or linear, a few 
hundred yards in extent. It is locally believed that the underground 
streams associated with the sinks drain not only the pine land, but help 
to drain the Everglades to the west, because great springs of constant 
flow emerge in large numbers along the shore. This is probably true, 
but the interior drainage perhaps escapes by percolation, or very small 
channels, for no sinks were seen in or near the Everglades. Тһе pines 
cover a shore strip about six miles wide between New and Miami Rivers, 
then widening to about fifteen miles in the next twenty-five miles 
toward the southwest. The southwestern terminus of the pines is not 
known. 
The Everglades. — A great area of Southern Florida west of the pine 
belt comprises the Everglades. The cause of the Everglades would seem 
to be similar to that for the prairies among the pines, — a drainage so 
defective that much water accumulates during the rainy season, and 
some even continues through the dry time, though the change in eleva- 
tion is perhaps two feet. Temporary surface channels to the sea help 
drain the Everglades during the rainy season, but only the larger rivers, 
as the Miami and New, flow throughout the year. Тһе rivers have a 
well marked fall line on the limestone, — a few hundred yards of swift 
water just west of the pines, and representing the progress made by the 
rivers in cutting back from their mouths. 
At the border of the Everglades the rough surface of the oólite 
becomes concealed for the most part beneath a mat of grass, and pines 
grow no farther west (Plate XXIV. Fig. 1). In the zone of oscillation 
of water the grasses change in character from a small wiry variety near 
the pines to saw-grass six feet or more tall, and flags and cane growing in 
water. The Everglades impress one as a sea of grass growing in shal- 
low water, with countless shallow ponds of clear water in which grow 
