Central Oregon is festooned with a host of rather unique geological features.  The highly visible and accessible nature of these features in central Oregon provides the primary motivation for this website; few other places in the world offer such a plethora of outstanding landforms and exposures of rock and sediments within easy reach.  Volcanoes and their associated lava flows and pyroclastic materials abound.  All types of volcanoes and eruptive products are found.  Many of these volcanoes show recent signs of eruptive activity; some are considered active.  Volcanic vents may be surrounded by spatter cones built of congealed blobs of cow-pat-like lava, or larger cinder cones breached by lava flows that poured from their flanks.  Lava flows may exhibit tree molds where they enveloped whole forests, or giant gas bubbles where escaping gases coalesced and were trapped within viscous lava.  Long buried lavas and sedimentary deposits now exhumed in deeply dissected canyons provide clues about the early rise of the Cascades.  Faults in the region tell of recent and continued extension, rotation, shearing, and fracturing of the earth’s crust.   Living glaciers still occupy the higher flanks of many volcanoes, while evidence of their once much greater extent is easily spotted with a bit of training in the river valleys that drain their lower slopes.  Several flat-floored basins display landforms and sedimentary deposits that preserve evidence of former lakes associated with cool, moist glacial conditions, long since dried up and now occupied by sagebrush-covered sand dunes; volcanic features in some basins show signs of having been erupted through saturated sediment near or beneath the floors of these lakes.

The primary intent of these geological guides is to summarize in a single publication all of the currently available information on the geology of the central Oregon Cascade Range and areas immediately to the east, and to provide accurate descriptions of how to reach many of the classical geological settings and features found there, either by car or by foot.  But there is another purpose; as an avid outdoor enthusiast and practicing glacial geologist, some of this author’s fondest memories are of the camping, hiking, backpacking, and research experiences he has had in the wilds of central Oregon.  This author felt that the profoundly beautiful scenery witnessed and the knowledge gleaned from my travels needed an outlet and the undergraduate college professor in me demanded a generalist’s approach; and thus, were these geological guides conceived and written.  The intended audience is a general public interested in outdoor recreational activities and inquisitive about natural history, as well as students and teachers of earth science and ecology; and it should also serve as a useful reference for geologists and other natural science professionals.  The ‘central’ in central Oregon represents a broad region roughly centered on the community of Bend, Oregon that includes that portion of the Cascade Range generally lying within the area encompassed by the upper McKenzie and Deschutes River watersheds, as well as the area surrounding Newberry Volcano and the Fort Rock – Christmas Valley – Silver Lake basin (Figure 1).

Figure 1. A map showing the area of central Oregon.

Figure 1.  A map showing the area of central Oregon described in this guidebook; field trip routes are highlighted in color.

The guides begin with this brief ‘how to’ on the most efficient use of these publications, followed by some good advice for a safe and low impact outing.  As an additional source of information, perhaps of limited interest to all but those true academics, this author has included an exhaustive list of references cited in the text of the field guides (listed alphabetically, and where an author’s name appears more than once, from the most recent citation, backward).  Be sure to refer to the GEOLOGY BASICS and GEOLOGY OF CENTRAL OREGON web pages for further information on the basic physical geology concerning many of the significant features that one may encounter in the field, more detailed descriptions covering volcanology and glacial geology highlighted on in these guides, and a final section that summarizes the regional geology and geologic history of the Oregon Cascade Range.  Each guide found in the FIELD GUIDES TO CENTRAL OREGON’S GEOLOGY is devoted to the description of a specific geological field trip including one or more road logs detailing geological points of interest, descriptions of optional hiking trails that get you off road and closer to the action, and accompanying diagrams, photographs, and maps.  Where relevant, this author’s own research is discussed.

Preparation (Before You Head into the Field)

Any intended geological touring of central Oregon should begin with knowledge.  For those of my readers that lack a background in geology, you are strongly encouraged to read the GEOLOGY BASICS and GEOLOGY OF CENTRAL OREGON web pages before embarking on any of the field trips described later in the FIELD GUIDES TO CENTRAL OREGON’S GEOLOGY.  Although these latter publications do not cover every aspect of central Oregon’s geologic features, they were developed to be as comprehensive as possible, without sacrificing readability and digestibility for the natural history enthusiast.  The GEOLOGY BASICS web page summarizes many fundamental concepts of physical geology, and describes numerous geologic features and processes significant to central Oregon’s geologic setting; it also provides a GLOSSARY OF GEOLOGIC TERMS.   The GEOLOGY OF CENTRAL OREGON web page is subdivided into three sections focusing on features and processes related to volcanism and glaciation respectively, and a brief overview of central Oregon’s regional geologic setting and geologic history.

The geological field guides presented in FIELD GUIDES TO CENTRAL OREGON’S GEOLOGY are the heart and soul of this website, their content should not be missed when planning an excursion into central Oregon.  Four field trip routes suffused with classical geological features are included in this chapter (Figure 1) and are primarily described in terms of auto-touring road logs, although they are readily adaptable to bike-touring; and all routes include descriptions of hiking trail options (for those seeking to get off the more beaten paths).  Each field trip road log is laid out in route segments with descriptive text, photos, figures, and accompanying topographic and/or geologic maps.  For each route segment, the mileage between adjacent segments is provided, as well as the cumulative mileage for the entire route.  As an example, specific locations or geologic features on a road log might be given as 12.3 (3.4), meaning that the total distance from the route’s beginning is 12.3 miles, and that the distance from the previously described mile-marker is 3.4 miles.

Route segments each follow a designated road generally suitable for passenger cars, but many segments include options for hiking on trails to explore geologic features unreachable by car.  These road routes would also be suitable for bike touring, although some routes or portions of routes may be better suited to off-road bikes.  Road surfaces along the routes vary from pavement to packed earth (dirt).  Roads surfaced with crushed rock, gravel or dirt can be dusty and rough depending on usage and maintenance; a not-so-pleasant phenomena known as “washboarding” is a common feature on gravel roads, especial if not recently graded.  All limited-maintenance gravel roads and unmaintained dirt roads were driven by passenger car during preparation of this guidebook, but care should be taken when driving these roads depending on the type of vehicle in use and the driver’s experience.  Descriptive text in the guidebook includes advisements on current rough road conditions, although be aware that some roads are poorly maintained or not maintained at all, thus ‘current’ conditions described in this guidebook will become dated with time.  Be sure to carry adequate gas, food, water, and camping gear for emergencies; and check local accessibility on secondary roads prior to departure in late fall, winter, and early spring.  A cell-phone is useful in many areas, but reception is spotty at best in the Three Sisters area, inside Newberry Volcano, and on its southeast flank.

Each field trip route description is accompanied by color shaded-relief map reproductions of each USGS 7.5 minute topographic quadrangle that is traversed.  Each map contains the road route currently being described, plus mile-markers for each route segment that indicate points of interest detailed in the guidebook’s text.  Hiking trail route maps are included, reproducing appropriate quarter sections of each 7.5 minute quadrangle at a larger scale and greater detail.  Figure 2 provides a key to the symbols used on these two types of map.  These maps are located at the end of each field trip’s road log and optional hiking trails sections, respectively.  Route descriptions on federal and state highways, county roads, Forest Service and Bureau of Land Management roads are given in tenths of miles from certain easily located road or trail intersections and from previously described features along the route (hiking trail distances are given in to the nearest hundredth of a mile); road mileage was obtained from standard dashboard odometer, while hiking trail mileage was obtained using a Delorme Earthmate PN-60.  Many sites are described with reference to significant landmarks, geographic features, or milepost markers located at specific intervals along the edge of most roadways.  Route descriptions also use standard compass bearings (such as northeast, southwest) and/or hourly positions on a clock (assuming 12:00 is due north) to indicate where to look for certain geological features.  For example, a description may read “feature located to the east” or “feature located at 3:00”, indicating that the feature at hand can be readily observed from a certain road position when looking in that direction.  Route descriptions also use various abbreviations: BLM = U.S. Bureau of Land Management, FS = U.S. Forest Service, Hwy = highway, Rd = road, and Tr = trail.  In this case, a road intersection might read as “The intersection of FS Rd 14 and county Rd 12A”.

Figure 1.2

Figure 2.  Symbols used on field trip road and hiking trail route maps described in FIELD GUIDES TO CENTRAL OREGON’S GEOLOGY.

Maps showing the general topography and all roads in the area can be obtained from the U.S. Forest Service and U.S. Bureau of Land Management.  Several types of maps at a variety of scales exist, drawn at different levels of detail depending on their purpose, but particularly useful is the Deschutes National Forest Bend Ranger District and Sisters Ranger District recreation maps and the Willamette National Forest McKenzie Ranger District recreation map which include much of the area described in this guidebook.  The U.S. Geological Survey also publishes7.5 minute topographic maps of the entire United States; the original name of the USGS 7.5 minute quadrangle is always indicated on the shaded-relief maps used in this guide and the author encourages readers to obtain copies of the original maps if greater detail is desired, especially useful while hiking.  Figure 3 displays each road trip route superimposed on a grid of the topographic map coverage for that field area; Figure 3a covers the Field Guide to the Bend Area, Figure 3b covers the Field Guide to the Cascade Lakes and Willamette Pass Areas, Figure 3c covers the Field Guide to Newberry Volcano and the Christmas Valley-Fort Rock Area, and Figure 3d covers the Field Guide to the McKenzie Pass and Santiam Pass Areas. Also recommended is a copy of 100 Hikes in the Central Oregon Cascades (Sullivan, 2008); many great hikes are described therein, and it includes a treasure-trove of information on camping and hiking regulations, safety tips, and etiquette.

Field Trip 1

Field Trip 2

Field Trip 3

Field Trip 4

Figure 3.  The four road trip routes presented in the field guides are superimposed on a grid of USGS 7.5 minute topographic map coverage corresponding the field area; (A) covers the Field Guide to the Bend Area, (B) covers the Field Guide to the Cascade Lakes and Willamette Pass Areas, (C) covers the Field Guide to Newberry Volcano and the Christmas Valley-Fort Rock Area, and (D) covers the Field Guide to the McKenzie Pass and Santiam Pass Areas.

Backcountry Safety and Responsibility

During the preparation of these field guides, I was keenly aware that my backcountry experiences are probably a tad greater than average, and that my environmental ethics might be honed to a greater degree of sensitivity than the typical weekend camper.  Any adventure into the “wilds” of central Oregon should not be taken lightly.  Anyone who spends a significant time in the out-of-doors knows that doing so comes with a certain level of personal risk and potential environmental impact.  Enjoy, but do so wisely, carefully, and respectfully.

My safety suggestions are simple.  First, carefully plan your itinerary; these field guides should aid you well in this endeavor.  Second, make sure someone knows approximately where you’ll be and when you’ll be there, so that the authorities can be notified if you fail to appear.  If you get into trouble, stay put, stay warm and dry, and someone will find you.  Third, don’t do anything that you don’t feel comfortable doing because in all likelihood, it falls outside your realm of knowledge and skills, or it is inherently dangerous.  Taking risks can be rewarding, but too much of a good thing can get you in harm’s way fast.  Fourth, know what you are about when you head into the field, or take someone with you who does.  While I have tried to describe each hiking route in detail, including the rather excellent maps contained within the field guides, my descriptions and maps should not be considered a substitute for good map reading and route finding skills.  I have deliberately avoided using trail ratings in my field guides; the fact that a hike is included in these guides, no matter what rating I might give it, does not mean it will be safe or easy for you.  And don’t be overly reliant on your hand-held GPS either, satellite signals can be poor in dense forest and rough terrain, and batteries can fail.  Figure 3 offers index maps to the original USGS 7.5 minute topographic maps covered by each field trip in this guidebook; and of course, there is no substitution for the originals when planning and executing an excursion into central Oregon’s wild areas.  Fifth, carry the right equipment.  Travel in out of the way places can be challenging enough, but rough weather or a wrong turn can make the proper gear a lifesaving prospect.  The ten essentials you should have in your backpack include: 1) drinking water; 2) extra food; 3) a first aid kit; 4) a flashlight or headlamp; 5) fire-making materials (fire-starter and water-proofed matches or a butane lighter); 6) rain gear; 7) a topographic map; 8) a compass; 9) a pocket knife; and 10) emergency shelter and/or extra clothing.  Notice that a cell-phone didn’t make my list; cell-phone signals are spotty at best in much of central Oregon.  Encounters with large wild animals are extremely rare in the Oregon Cascades; nuisance chipmunks and mosquitoes on the other hand are quite common.  Rodents raiding your food can be avoided by using proper storage containers (I use 5-quart tin paint cans).  Mosquitoes remain a problem until several weeks after snowmelt, so expect them at least through mid-July at higher elevations.  Travel by car may be inherently safer, but not without risk.  Some locations in these field guides are a long way from anywhere so in addition to the supplies above, bring an extra key to carry with you with you leave the vehicle, and bring extra water and a good spare tire for the vehicle too.

Please minimize your impact when travelling in the backcountry; personally, I recommend following Leave No Trace principles (www.lnt.org): 1) plan ahead and prepare; 2) hike and camp on durable surfaces; 3) dispose of waste properly; 4) leave what you find; 5) minimize campfire and camping area impacts; 6) respect wildlife; and 7) be considerate of other visitors.  Hike on established trails whenever possible, and do not shortcut switchbacks or “trail” around mud, standing water, or snow-covered patches.  In areas where there are no established trails, avoid trammeling on delicate alpine and subalpine vegetation whenever possible by using rock outcrops, stones, snow, or dry grasses and sedges if need be.  Choose a campsite well away from trails, streams, and shorelines, preferably in an established location; and never on meadow vegetation.  Avoid campfires; cook with a camp stove and wash at least 100 feet from the water’s edge.  Please pack out all of your trash (even so-called “natural” material such as orange peels can take years to decompose; and the natives don’t need to eat your leftovers anyway).  Consumption of edible berries is certainly a perk of your outdoor adventuring, but don’t pick the wildflowers or carve your name in the trees please.  A parking permit is required at many of the National Forest trailheads described in this book (obtained from a number of outdoor stores or online for $5.00 per vehicle per day).  Alternatively, if you plan to do a good deal of recreating, you might want to purchase a $30.00 per vehicle Annual Northwest Forest Pass (www.discovernw.org).  Special rules apply to designated Wilderness Areas.  From the last weekend in May through the end of October, a hiking/backpacking permit is required for certain Wilderness Area locations (inquire at the relevant National Forest website or ranger’s station).  Many other restrictions pertain to camping in Wilderness Areas and should be observed: 1) groups must be 12 people or less; 2) camp in designated sites only if available; 3) no campfires within 100 feet of trails or water; 4) do not enter rehabilitation areas; 5) bicycles and other wheeled vehicles (except wheelchairs), motorized equipment, and fireworks are not permitted; 6) riding horses and pack stock cannot be tethered within 200 feet of water; and 8) do not cut or damage live trees and shrubs.  Collecting plants is by permit only, and the collection of cultural artifacts (arrowheads and the like) is a crime on all federal lands.

Are you ready to get out there?  Don’t forget to pack your guide.  Please drive and hike safely; slow down, and get out of your car often; take a hike, brave the elements, work up a sweat, and get your hands dirty.  It’s the only way to SEE the world.