84 FLORIDA GEOLOGICAL SURVEY ELEVENTH ANNUAL REPORT. 
LIMESTONE. 
The limestones of this area have been used quite extensively in 
the construction of buildings, for foundation work and for chimneys. 
The limestones are found principally in the northern part of the area 
particularly in Jackson County in the vicinity of Marianna and the 
northern part of Washington County a few miles south of Chipley. 
The limestones of the. Ocala and Marianna formations are very soft 
and friable and are cut with a cross-cut saw into desired size blocks 
for construction purposes. Upon exposure these blocks become 
more or less hard and make a very desirable building block. This 
limestone runs uniformly high in calcium carbonate and contains but 
little foreign impurities. It should make a good material for agri- 
cultural purposes as well as for the manufacture of a high grade 
lime. 
PHOSPHATE. 
The Alum Bluff formation, which is frequently seen in the stream 
banks, is often, here as elsewhere, more or less phosphatic. Some 
attempt to get phosphate from this formation on Econfina Creek was 
made some years ago. A company was organized under the name 
of the Econfina Phosphate Company and a small plant constructed. 
From the banks of the Chipola River below Clarksville samples of 
the sand rock of the Alum Bluff Formation were found to be slightly 
phosphatic. No localities are known in this area, however, which 
appear to contain workable phosphate deposits. 
ROAD MATERIALS. 
The principal road building- materials of this area are sandy 
clays, limestones and gravel. The clays are very generally distrib- 
uted over the northern part of the area and are extensively used in 
surfacing roads. The limestones have been but little used as road 
metal. The gravel found in the northern part of the area is now be- 
ing quarried and used in the construction of the roads of Bay 
county. 
SANDS AND GRAVELS. 
Some of the best and most extensive deposits of sands and gra- 
vels occurring in Florida are found within this area. These are 
quite generally distributed from the southern part of Jackson county 
