Named for outcrop in Tolovana Valley but best exposures are in White Mountains, about 50 mi north of Fairbanks, Yukon-Tenana region, east-central AK. Farther southwest unit is present on end of ridge between Tatalina and Tolovana Rivers and farther southwest in low hills west of Tolovana embayment (making total of more than 60 mi). Composed entirely of carbonate rocks including limestone and dolomite. Limestone in White Mountains is dark to light gray, crystalline and weathers white, yellowish or buff. In White Mountains unit is infolded with Fossil Creek volcanics (new) of Middle Ordovician age. Unconformably underlies later Devonian rocks. Age is Silurian based on considerable fauna identified by Edwin Kirk (list and localities included in report).

Source: GNU records (USGS DDS-6; Menlo GNULEX).

Age is Early(?) Silurian (Llandoverian?) to Middle Devonian based on corals (as shown in correlation charts).

Source: GNU records (USGS DDS-6; Menlo GNULEX).

In White Mountains Tolovana Limestone is Silurian age, but in locality C (65 deg 36'34"N, 147 deg 19'57"W) which is southwest of White Mountains proper, conodonts recovered from basal beds of Tolovana Limestone indicate Middle Ordovician to Middle Devonian though probably Silurian age. Silurian age is confirmed by associated megafauna including pentamerid brachiopods.

Source: GNU records (USGS DDS-6; Menlo GNULEX).