196 FLORIDA GEOLOGICAL SURVEY I3TH ANNUAL REPORT 



294 days at Ocala (and doubtless still less a little farther north) 

 to practically 365 on Merritt's Island and south of there, where 

 often a whole year passes without frost. (The imaginary "frost 

 line" lies considerably farther south, however, for there is prob- 

 ably no place in Florida, with the possible exception of the Keys, 

 that has not had frost at some time within the memory of persons 

 now living. ) 



Although it is not feasible to present figures on that point, the 

 temperature of course varies from year to year, and some of these 

 variations have made the difference between success and failure 

 for those who are always trying to raise tender crops as far north 

 as possible. The severe freezes of 1895 ^.nd 1899 almost wiped 

 out the orange industry in Florida (which was then largely con- 

 centrated in the latitude of Ocala and farther north), but since then 

 many of the larger groves have been established farther south, and 

 more attention has been paid to locating them on high points 01 near 

 lakes for protection from frost, and installing heating devices to 

 use at critical periods, and there has been comparatively little trouble 

 from that source in the last twenty years. The lake region has 

 an advantage over most of the others in its abundance of hills and 

 lakes. 



Snow is of course practically unknown. The extreme variation^ 

 in rainfall from place to place are not great, but the lake region 

 seems to be a little the driest, perhaps because farthest from the 

 coast. Although there may be considerable variation from year 

 to year, it is hardly enough to cause any serious inconvenience, for 

 there is nearly always enough rain to prevent drought, and at the 

 same time the topography and soil make floods almost impossible. 

 On the sandy uplands the heaviest rain sinks into the ground al- 

 most immediately, to appear gradually later in swamps and springs. 



Over half the rain falls in the four warmest months, and over 

 two thirds in the six warmest months, thus counterbalancing evap- 

 oration to a large extent and keeping the level of lakes and streams 

 more constant than in most other parts of the United States. A 

 slight correlation can be noticed betv^een the late summer precip- 

 itation excess and soil fertility, the excess being less in the hammock 

 belts than in the lake region and flatwoods ; as if the soil itself 



