Geology

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GEOLOGY

ASSESSMENT Of PROPOSED PIONEER MEADOWS SUBDIVISION
CONTAINING APPLEGATE TRAIL RESOURCES

IV.A. Geology

Geologically almost all of Section 14, and most of the Proposed Pioneer Meadows Subdivision, is identified as di = "Quartz diorite and related rock."¹ Quartz diorite and related rock (di) includes hornblende diorite, granodiorite, and a few dacite and diabase dikes. Where decomposed is source of common fill (i.e., decomposed granite). Pegmatite veins contain high-purity quartz and feldspar. Minor gold, copper, and molybdenite mineralization occurs in "di" near contacts with older rocks.

Locally folks know about decomposed granite derived from the Grants Pass pluton’s granitic soils. Decomposed granite in Josephine County comes from a general soil map unit identified as Holland-Barron-Siskiyou.² The soils in this general map unit are in areas dominated by moderately deep and deep, well drained and somewhat excessively drained soils on hillsides, toe slopes, and alluvial fans. When the soils in this group are disturbed, the hazard of erosion is high

A small part of the northwestern portion of the Proposed Pioneer Meadows Subdivision in Tax Lot 1900 is geologically quaternary sediment.¹

1. Ramp, Len, compiled by. 1979. Geologic Map of Josephine County, Oregon. State of Oregon Department of Geology and Mineral Industries.

2. United States Department of Agriculture. Soil Conservation Service. December 1983. Soil Survey of Josephine County, Oregon. (0R033) (Now Natural Resources Conservation Service (NRCS).