Heads at glacier, flows NE to the Little Nechina River, S of Horsepasure Pass, 19 mi. NW of Tahneta Pass, 96 mi NE of Anchorage, Talkeetna Mts. 6.8 miles long.
Named in 1956 by U.S. Geological Survey (USGS) "for the abundant occurrence of well-preserved ammonites (fossils) belonging to the genus Cardioceras."
Horn Mountain, Syncline Mountain,
Mountain Passes:Horsepasture Pass, Limestone Gap,
Mountain Ranges:Streams:Alfred Creek, Ammonite Creek, Bench Creek, Billy Creek, Bubb Creek, Cadoceras Creek, Cardiceras Creek, Cardioceras Creek, Chitna Creek, Conglomerate Creek, Divide Creek, Flume Creek, Gold Creek, Granite Creek, Greta Creek, Horsepasture Creek, McDougall Creek, Mouse Creek, Papoose Creek, Pass Creek, Sawmill Creek, Sawmill Creek, Sheep Creek, Shovel Creek, Sladen Creek, Whistler Creek, Wood Creek,
Valleys: