4]

F4l. Geol. Surv. Cat. No. 3487 Locality: northeast side of peak 23 miles southeast of mouth of Attichika Creek. Conifers Sequoia langsdorfii (Brongniart) Heer Angiosperms Platanus reynoldsii Newberry var. integrifola Lesquereux Trochodendroides arctica Heer Populus carneosa (Newberry) Corylites hybridica? Seward and Holltum Celastrinites insignis (Heer) ef. Oreodaphne coushatta Berry Myrsinophyllum groenlandicum (Heer) Rhamnites sp. Pterospermites sp. Age: Paleocene

F42. Geol. Surv. Cat. No. 3488 Locality: 3 miles east-northeast of mouth of Niven River.

Ferns Sphenopteris (Asplenium?) cf. S. miertschingi Heer Aneimia sp. (fertile) Conifers Sequoia langsdorfii (Brongniart) Heer Sequoia sp. (with foliage like many American specimens referred to Glyptostrobus europaeus, and cones smaller and more oval than those of Sequoia couttsiae (Heer) Elatocladus (Taxodites?) tinajora (Heer) Angiosperms

Viburnum contortum Lesquereux Age: probably Paleocene, not later than lower Eocene

Age The paleontological evidence indicates that the formations of the lower division belong, in places, to the lower part of the Upper Cretaceous epoch, and those of the upper division to the Paleocene. As no stratigraphic break has been recognized within the Sustut assemblage, the entire Upper Cretaceous series may be represented.

KASTBERG INTRUSIONS Distribution

The Kastberg porphyritic intrusions are confined, with possible minor exceptions, to that part of the map-area lying south and southwest of Mount Carruthers. They are particularly well displayed in the vicinity of upper Kastberg Creek between Scallop Mountain and Comb Peak, and on the east slope of Bear Lake Valley.

Inthology

The rocks of the Kastberg intrusions are grey, buff, or rarely pale pink, generally distinctly porphyritic rocks, commonly thoroughly weathered to a depth of half an inch or more. This deep weathering has resulted in a characteristic soft chalky appearance as well displayed by the numerous erratic boulders and slabs seen along the trail a few miles southwest of Yuen Lake. Although these intrusions vary widely in grain size the most