Collection from Cape Thompson sea-cliff section. (from faunal list given on Table 2, pp. 8-9 in Campbell, 1967)

The Nasorak Formation (Campell, 1965a) is a limestone sequence named from typical exposures in sea cliffs near the mouth of Nasorak Creek (pl. 2B), where nearly 1,800 feet of the upper part of the formation are nearly continuously exposed with relatively little structural complexity. (from Campbell, 1967, p. 7)

Fossils are relatively abundant. The identifiable forms are chiefly Bryozoa (predominately fenestrate), brachiopods, horn corals, lithostrotionoid corals, and a few endothyroid Foraminifera. The megafossils were examined by J.T. Dutro, Jr., and Helen M. Duncan, of the Geological Survey, who conclude (written commun., 1961) that collection from the upper 1,500 feet of the Nasorak Formation (table 2) indicate equivalence to the lower part of the Alapah Limestone (Upper Mississippian) of the central and eastern Brooks Range, and those from the lower approximately 500 feet indicate correlation with the upper part of the Wachsmuth Limestone (Lower Mississippian). They also conclude that the basal 165 feet of the Nasorak contains fossils that correlate with those of the Utukok Formation (Lower Mississippian) of the western DeLong Mountains (Sable and Dutro, 1961, p. 591-592) and that the fossils of the remaining 1,935 feet of the Nasorak are equivalent to those in part of the Kogruk Formation (Lower and Upper Mississippian) of the western DeLong Mountains (Sable and Dutro, 1961, p. 592). Apparently, then, the beds of the Nasorak Formation represent continuous deposition from Lower Mississippian at the base to Upper Mississippian at the top. The formation is accordingly assigned an Early and Late Mississippian age; the lower member and Cape Thompson Member are included in the Lower Mississippian part, and the boundary betweeen the Lower and Upper Mississippian lies in the lower part of the upper member. (from Campbell, 1957, p. 14)

(Referring to unit 6 of the upper member of the Nasorak Formation on p. 31 of Campbell, 1967): 59ACr-123f is a fossil collection (table 2).

They can be correlated in a broad way with the Mississippian sequences in the central and western Brooks Ranges. The collections are discussed from the top down.

Unit Ml₄ appears to correlate with the upper part of the Alapah limestone of the central Brooks Range. Because most of unit Ml₄ represents a different facies from the type Alapah, the faunas have a different aspect. Several collections represent a "Chester"-type assemblage of bryozoans, brachiopods, and echinoderms. Collection 55 best represents this assemblage, with Archimedes and Pentremites and several kinds of brachiopods.

In a broad way, these collections correlate with the Gigantoproductus zone of the central Brooks Range. Gigantoproductus has been found in similar rocks near Cape Lisburne, north of the Point Hope area, although none appear in this shipment.

Collections above 56 are poorly preserved in a dolomitic matrix and cannot be definitive in terms of age or correlation.

Unit Ml₃, except for the basal part, is probably equivalent to the lower part of the Alapah limestone. There is a wide variety of lithostrotionoid corals, like those found in the Lithostrotion aff. L. asiaticum (Yabe and Hayasaka) through Sciophyllum lambarti (Harker and McLaren) zones of the central Brooks Range sequence.

The basal part of unit Ml₃, including collections 11, 12, 13, 123 and 122, is probably correlative with the upper part of the Wachsmuth limestone, the Brachythyris suborbicularis (Hall) zone.

The single collection from Ml₂ contains no definitive fossils but since this unit is bracketed by Wachsmuth age collections, it too can be be considered a correlative of the upper Wachsmuth.

Collection 119, from unit Ml₁, also represents the upper part of the Wachsmuth and is similar to collection 123. Therefore, units Ml₁, Ml₂ and the lower part of Ml₃ can be considered of Osage age.

Unit Ml₁, and the upper part of the unnamed clastic unit below, I would consider equivalent to the Utukok Formation of the western De Long Mountains. Units Ml₂, Ml₃ and probably Ml₄ would be equivalent to the Kogruk Formation. Unit Ml₅ is a Tupik equivalent. I suspect that repetition by faulting may have resulted in too thick a measurement for unit Ml₄ and too thin a measurement for Ml₅. In 1951, we measured at least 490 feet of the Ml₅, Tupik equivalent. From the measured sequence, as transmitted with the examination request, I would suggest that only about 2400 feet is certainly assignable to Ml₄. The upper part may be repetitions of Ml₄ and Ml₅. In addition, there is evidence of intertonguing of the Ml₄ and Ml₅ facies, not only in the Point Hope area but also in the central Brooks Range. This usually complicates any cut-and-dried formations in the upper part of Alapah equivalents.

Collection 119, from unit Ml₁, also represents the upper part of the Wachsmuth and is similar to collection 123. Therefore, units Ml₁, Ml₂ and the lower part of Ml₃ can be considered of Osage age.