144 FLORIDA GEOLOGICAL SURVEY-I3TH ANNUAL REPORT

 Shell mounds built up centuries ago by the aborigines are rather common along the lagoons, and many of them have been excavated for road-surfacing material (Fig 34). Flowing artesian wells, with more or less sulphurous water, can be had anywhere, and in some places the pressure is sufficient to run dynamos or other machinery.
 The ancient dunes west of the Indian River (fig. 31) are in some places about 50 feet above sea-level, but this is probably due largely to an uplift in comparatively recent times, for the modern dunes next to the ocean are much lower. The outer beach in Volusia County is one of the most noted natural automobile racecourses in the world, and speeds of 156 miles an hour have been recorded there. The Indian River and other shallow salt lagoons behind the barrier beaches are navigable for small vessels, and in recent years they have been connected by dredging canals through intervening marshes and strips of sand, so that there is now an inside passage all the way up the coast to South Carolina. There is practically no tide in these lagoons, on account of the inlets being small and far apart.


















 Fig. 29. Scene in Turnbull Hammock, a typical low hammock, about a mile west of Daytona, Volusia County. By E. H. Sellards, May 21, 1910.
 Soils. The soil survey of the "Indian River area," published in 1915, covers most of Merritt's Island and the neighboring barrier beaches, and a little of the near-by mainland, giving a very typical