Six of these 7 collections appear to be related and are probably of Late Triassic age. Except for 72ARh-400 and 72ARh-432, they represent a coralline facies that has seldom been encountered in central Alaska, to my knowledge. Similar assemblages do occur along the northwestern Pacific coast and in southeastern Alaska (see Smith, J.P., Prof. Paper 141, 1927).

The most convincing and diversified collection is 72ARh-433 which a several large spongiomorphids and two or three kinds of hexacorals plus a few snails and small brachiopods. Collection 72ARh-428 also has definite hexacorals that indicate post-Paleozoic age.

Our difficulty is that no one in North America is currently actively studying early Mesozoic corals. If some definite generic and specific determinations could be made, a precise age assignment should be possible. This preliminary report, based on a rapid examination of external morphology is to alert you to the post-Paleozoic age of these rocks. Some of the material will be dissolved in acid to recover the silicified shells; the rest will be preserved for future study.

[Transmittal form contains following statement from Richter: "Fossils being sent in this shipment were collected from a number of massive limestone units overlying and structurally enclosed by, amygdoidal basalt of apparently Triassic age. An earlier collection of fossils from this area did not prove diagnostic (Shipment A-67-2, report 6/13/67). Detailed mapping by Richter in August 1972 to better define the structure in the area resulted in this much better suite of fossils. The 1967 mapping and fossils suggested the possibility that some of the limestone units may be structurally emplaced Permian Mankomen Formation which is exposed due west across the Slana River."]