Calendar

Past Activity

Horse Rock Geology

  • Start date: 05/19/2018

  • Start time: 12:00 AM

  • End date: 05/19/2018

  • End time: 11:59 PM

Description:

From the trail head we will hike through small pine stand into a meadow, then along a narrow grassy ridge. Our destination will be an eroded volcanic vent and radial dyke that erupted roughly 30-36 m.y.a. This is close look at rocks that formed the old Western Cascade volcanic arc some 28 m.y. before the High Cascade volcanic ark formed about 2-3 m.y.a. If we are lucky, there will also be a few early wildflowers and a good view of the South Willamette Valley.

  • Event Leader: Tom Rundle

  • Event Leader Phone: 541-653-0741

  • Event Leader Email: vivadancero@gmail.com

  • Assistant Leader:

  • Event category: Trips

  • Area Type: Mountain

  • Departure Location: Amazon Park, 28th & Hilyard entrance parking lot

  • Rating: Easy

  • Roundtrip total drive miles: 44

  • Season: 2018

  • Permits Required:

  • Event Status: Passed

  • Supplies and Equipment Required: Water, snack, lunch, trail shoes or boots, attire appropriate for weather

  • participant prerequisites:

  • Conditions:

  • Total Distance: 3.2

  • Member Fees: 1

  • Elevation Gain: 630

  • Non-Member Fees: 5

  • Committee: Trips

  • Junior member fees: —

Trip Report

Early half of the hike was foggy with about 400 yards visibility. Wildflowers were amazing. We were probably close to the peak of the season. We had lunch at the radial dyke followed by a talk about the local geology, the geologic history of the Western Cascades. We also looked a some geologic maps of major faults, anticlines and synclines of the Willamette Valley which assess seismic hazards from Springfield to Salem. And we briefly talked about Missoula and Bonneville Floods that inundated the Willamette Valley over the last 20,000 years. After lunch the fog lifted and we could see a few miles across the adjoining ridges and valleys.