Volcanic Ramblings

As I've mentioned, I'll be doing some geotripping next week, and the schedule looks as if it's been bumped up a day. Which means it's a day closer than it was when I woke up this morning, and in turn, that I'm even more excited than I expected to be. I have had the itinerary basically worked out for the last two months. By "basically" I mean that in the many, many trips I've done with high schoolers and middle school students, I've found that it's important to plan a certain amount of flexibility into one's expectations. Spur-of-the moment decisions can lead to unexpected and terrific discoveries. So I think of a trip itinerary as a framework to be built onto as needed. On the other hand, for safety (and sometimes communication) reasons, it's nice to have something that someone could point to and say "this is where they're supposed to be right now." A policeman might have some chance of finding a group that's in the neighborhood, but that's unlikely if they are two counties away.

I've also found that it's good to have a conceptual framework that you can tie things to. On Central and Southeast Oregon trips with high school-age students that framework was either how various differences in magma composition and environmental factors interacted to create different styles of volcanism, or how geologic factors (including- but not limited to- the landscape) interacted with the rest of the non-living world to effect the local biota. The conceptual framework I've been pondering for this trip more or less combines those two, and unites them in thinking about the large scale tectonic structure of Oregon: subduction, forearc ridge, forearc basin, arc, back arc rifting, and influences from the Yellowstone Hotspot, which made its presence impossible to ignore in Miocene Oregon. Basin and Range is still a little enigmatic to me, and I haven't seen anything that convinces me that the questions surrounding what drives that rifting have been satisfactorily settled. Nevertheless, it is certainly best explained in terms of tectonics; it's just that there are at least two approaches to doing that, and probably more, in addition to sliding scales of importance of this factor versus that factor.

All that said, here's the outline I just sent to the person sponsoring this volcanic ramble:

Day 1: (hoping we can set off from CVO mid-day/early aft.)

• Rt. I-5-> Eugene; Willamette seds, W. Casc. foothills
• Rt. 58 Eugene-> Crescent area http://www.flashearth.com/?lat=43.656335&lon=-122.225997&z=11.5&r=0&src=msl W. Casc, Salt Creek Falls, High Casc, E Casc. flank, Mazama ash

Day 2:

• Rt. 97-> N entrance Crater Lake, drive rim w/numerous stops, side trip to Pinnacles (inverted Mazama magma chamber)
• http://www.flashearth.com/?lat=43.146907&lon=-121.697854&z=10.1&r=0&src=msl
• Couple hour drive over to Lakeview & geyser http://www.flashearth.com/?lat=42.219802&lon=-120.369028&z=14.4&r=0&src=msl

Day 3:

• Rt. 140 E into N Nevada, Basin and Range volcanics. This grade will knock your socks off: drive up the side of a 1500 foot cliff! http://www.flashearth.com/?lat=42.037287&lon=-119.485068&z=13.1&r=0&src=msl Virgin Valley opals, opalized wood, badlands, Canyon hike, NICE hotspring if you feel like a leisurely soak http://www.flashearth.com/?lat=41.860943&lon=-119.006195&z=14.4&r=0&src=msl then back to Lakeview

Day 4:

• Rt. 395 N to Valley Falls, Abert Rim & Lake http://www.flashearth.com/?lat=42.530515&lon=-120.278008&z=10.7&r=0&src=msl
• Double back to Rt. 31, N to Summer Lake, Picture Rock Pass, Table Rock http://www.flashearth.com/?lat=43.165818&lon=-120.880866&z=12.3&r=0&src=msl Fort Rock http://www.flashearth.com/?lat=43.373231&lon=-121.068561&z=13.2&r=0&src=msl Hole-in-the-Ground http://www.flashearth.com/?lat=43.407399&lon=-121.194715&z=13.1&r=0&src=msl If time, a lava tube and associated spatter cone http://www.flashearth.com/?lat=43.526128&lon=-120.865433&z=15.9&r=0&src=msl Another possibility is Crack-in-the-Ground. http://www.flashearth.com/?lat=43.334696&lon=-120.673823&z=16.4&r=0&src=msl

Day 5:

• Newberry Volcano area- there are just too many possibilities here to list, figured we'd discuss and choose in preceding days or on the fly. http://www.flashearth.com/?lat=43.713128&lon=-121.233225&z=13.2&r=0&src=msl
• Head back to the Valley via McKenzie Pass: http://www.flashearth.com/?lat=44.243084&lon=-121.793236&z=12.3&r=0&src=msl and McKenzie River Highway http://www.flashearth.com/?lat=44.343641&lon=-121.99535&z=12.3&r=0&src=msl to Rt. 20, then into CVO

So skimming over this list, things to bring that you might not think of would include swimsuit/water wear if you're into hot springs, and flashlight/lamp. Bring a large container of water to keep in car (I generally carry 2 liters with me, try to keep at least 4 in the car), and smaller to carry with you. High elevation desert (Lakeview is over a mile in elevation, and it's on the valley floor), sunshine will be intense; hat and sunscreen. (Something I forgot to mention in this note is that the area is REMOTE, and very sparsely populated. Two hours or more between gas stations/stores of any kind is not uncommon, and that's assuming you're staying on main roads. In this area problems that might be minor elsewhere can quickly become life-threatening if you don't have basic supplies. Water is at the top of that list, and knowing places you can top off your supply is important.)

Okay I've spent too much time on this, but I think this is a good overview. Tectonically, we'll see a forearc basin (forearc ridge last fall), the evolution of a volcanic arc (W. Cascades are older, to ~30 Ma; High Cascades younger, <5Ma), and overlapping, complex magmatism related to the arc itself, back-arc rifting (possible early stage continental rift system) and hot-spot influenced magmas. I keep telling people that Oregon is overwhelmingly volcanic; we will see a few other rocks, but those are mostly sediments derived from erosion of volcanics.

I'm planning on taking the ol' electronical difference engine with me, in case we make meal or night stops that have wi-fi, but I make no promises that I'll actually post anything for a while. And even after I get back home, I will likely spend at least a day or few trying to high-grade my way through the better part of a week's intertubal accumulations.