site <- c("LA", "LA", "LA", "WR", "WR", "WR", "SS", "SS", "SS", "SS")
startdate <- as.Date(c('1601-01-01', '1836-01-01','1672-01-01','1912-01-01','1946-01-01','1835-01-01','1454-01-01','1672-01-01','1877-01-01','1978-01-01'))
enddate <-as.Date(c('1605-01-01','1841-01-01','1676-01-01','1918-01-01','1951-01-01','1839-01-01','1459-01-01','1676-01-01','1881-01-01','1983-01-01'))

data.frame <-data.frame(site, startdate, enddate)