What is the total number of areas by square mile where the founding year was 1785, the county seat was in Spartanburg, and the land area by square mile was more than 811?
CREATE TABLE "counties" (
  "county" text,
  "year_founded" text,
  "county_seat" text,
  "2010_census_population" real,
  "july_1_2012_population_estimate" real,
  "area_sq_mi" real,
  "land_area_sq_mi" real
);
SELECT SUM("area_sq_mi") FROM "counties" WHERE "year_founded"='1785' AND "county_seat"='spartanburg' AND "land_area_sq_mi">811;