2009 Summer Field Camp, First Segment (Ray Weldon)

The first 2.5 weeks of Field Camp will be taught by Ray Weldon and will focus on the active faulting and volcanism of Central Oregon. There will be four mapping projects and students will be required to complete three of them, to allow a little choice of project types and scales. The mapping will be on photographs (both air and ground-based photo-mosaics we will make of exposures) and on a topographic base that we will survey and contour. The projects and tools are designed to introduce students to the study of active surficial processes with a focus on active faulting and volcanology. We will also map late Pleistocene sediments and surfaces, that provide evidence for dramatic climate change in the region, as well as landsliding and other erosional processes.

Setting of the first half of Field Camp. Oblique Google Earth view of the 4 Craters, Crack-in-the-Ground fault and Green Mountain, where we will camp.

The first project will be to map the Four Craters Basalt Field, seen in the oblique image above. We will map on standard ~1:35,000 scale air photos, and the goal is to determine which flows came from which crater and the sequence of eruption of the four different craters. A student map from last year is included in the slide show related to this segment. The second project will be to map a small area where the Crack-in-the-Ground fault encounters the Four Crater flows (see below), using a topographic map we will make. We will use a combination of modern (differential GPS and Total Station) and classic (plane table) surveying techniques to establish the location and elevation of points that we will contour into a topographic map, and we'll then map the junction of the fault and basalt flows to better understand the sequence of earthquakes and eruptions.

Oblique view of the Crack-in-the-Ground fault and the edge of one of the 4 Crater flows.

The third and fourth projects will be conducted simultaneously so that students can choose which to pursue. Both will be mapped on photo-mosaics of vertical exposures (like making a cross section in which we can see what’s being sectioned!). One will be of a cliff face and will involve making a stratigraphic column of volcanic and volcaniclastic units and mapping them on the photo-mosaic across the cliff face; the other will be a trench exposure of an active fault cutting young lake sediments and tephras. Examples of a similar stratigraphic column and trench log can be seen in the related slide show.

Oblique view (looking north) of the northern end of Summer Lake basin. White arrows show the Ana River fault cutting down from the volcanic highlands onto the floor of the valley, that was a lake until ~13 ka (white lake sediments can be seen in the eroded area to the west of the fault). We will trench this fault to study surface rupture associated with earthquakes. Red arrows show cliff faces that expose the Pliocene volcanic and volcaniclastic sediments that underlie the volcanic highlands. We will make a stratigraphic column and map the extent of our chosen units across the cliff face on photographs.

We will camp out, share all of the camp logistics (Ray makes pancakes every other day!) and spend approximately 2 days field tripping within Central Oregon and the Cascades (well, at least the very eastern margin). There will be frequent trips into town for supplies and also opportunities to shower and phone home (some cell phones work in some parts of the field area). The weather will be warm (but not hot since we’ll be above 4000 feet) with some thunderstorms and spectacular stars.

See also: Ray Weldon's slide show for more related photos and graphics.