Abundant evidence supports the major contentions of the seafloor-spreading theory. First, samples of the deep ocean floor show that basaltic oceanic crust and overlying sediment become progressively younger as the mid-ocean ridge is approached, and the sediment cover is thinner near the ridge.irst, samples of the deep ocean floor show that basaltic oceanic crust and overlying sediment become progressively younger as the mid-ocean ridge is approached, and the sediment cover is thinner near the ridge.
Polk County Weather. The average temperature of Polk County is 72.96Â°F, which is higher than the Florida average temperature of 71.80Â°F and is much higher than the national average temperature of 54.45Â°F. Historical Weather. Heating Cost Index, #14.
Polk County Income and Careers. As of 2010-2014, the per capita income of Polk County is $21,157, which is lower than the state average of $26,499 and is lower than the national average of $28,555. Polk County median household income is $43,063, which has grown by 19.50% since 2000. The median household income growth rate is lower than the state average rate of 21.62% and is lower than the national average rate of 27.36%.