Onondaga Lake to the east, although smaller, is sometimes called "the 12th Finger Lake", because it is similar in shape. It is in Appalachian hill terrain, with a historic village linked to other Finger Lakes by US 20. It may have been formed in the same manner as the Finger Lakes, as satellite photos show three valleys similar in character and spacing to the Finger Lakes east of Otisco Lake. The first is the Tully Valley, which includes a chain of small lakes at the south end that could be a "Finger Lake" that never formed because of a terminal moraine. The moraine caused the Tioughnioga River to flow south instead of north, the opposite of the Finger Lakes' waters. The next two valleys to the east contain Butternut Creek, which flows north, and the East Branch of the Tioughnioga River, which flows south. The next valley contains Limestone Creek, which flows north. The next valley after that contains Cazenovia Lake.