THE ARTESIAN WATER SUPPLY OF EASTERN FLORIDA. 
91 
PLEISTOCENE. 
The marine Pleistocene deposits have been recognized at several 
localities ill eastern Florida. Messrs. Matson and Clapp obtained 
collections from Eau Gallie, Titusville and Mims in Brevard County. 
It is probable that marine Pleistocene shell deposits are somewhat 
widely distributed along the east coast and perhaps in the St. Johns 
River valley. Here again satisfactory determination can be made 
only from large and carefully kept samples obtained in well drill¬ 
ing. The coquina rock which occurs extensively at St. Augustine 
and extends along the coast to the south for 250 miles, is also to 
be placed with the Pleistocene. Some of the older sand dunes of 
the east coast also probably belong to the Pleistocene. 
EARTH MOVEMENTS DURING THE PLEISTOCENE. 
Changes in the relation of land and water have occurred recently 
along the east coast, probably during Pleistocene time. The best 
evidence of these changes is that offered by the sand dunes and 
the coquina rock bordering the east coast. The line of sand dunes 
along the coast is well developed and largely continuous. From 
Daytona south these dunes occur, not on the present beach, but back 
from the beach a variable distance depending upon the configura¬ 
tion of the country. At Daytona the sand dune lies back from the 
Halifax River about two miles. From Daytona to Titusville 
the dunes are to be seen lying mostly to the west of the East Coast 
Railroad at a distance of one or two miles from the coast. At 
Titusville the dunes lie back from the Indian River two to two 
and one-half miles. At Rockledge the dunes approach closer to 
the coast. They recede again, however, to the south and at no 
place directly face the ocean. The dunes are now quiescent and 
are covered with a thick growth of trees indicating that they have 
been undisturbed for a long time. In the same way the coquina 
rock, found facing the ocean at Anastasia Island in St 
Johns County, falls back from the coast to the south extending at 
places a few miles inland. The presence of this ledge of coquina 
rock bordering the coast together with the sand dunes lying back 
clearly indicates that the land level formerly stood lower than at 
present, the coquina rock and sand dunes having accumulated along 
what was then the beach. 
Conrad as early as 1846 noted the occurrence of marine shells 
of post-Pliocene age along the bank of the St. Johns River at an 
elevation of from ten to fifteen feet above the present high tide. 
