Tompkins County is divided by Cayuga Lake, the second longest of the glacially created Finger Lakes.  The lake, 435 feet deep at its core, with its headwaters at the southern end, is fed by streams that make their way through gorges cut in the underlying shale and limestone that make up the county’s geologic base.  The county today consists of 476.1 square miles; the southern end rugged terrain with Connecticut Hill reaching 2,095.97 feet.  The northern portion presents a more gentle and fertile terrain.