It’s hard to believe that 18,000 years ago a gigantic ice cap covered the Cascade Range, up to 2,000’ thick and 170 miles long. Glaciers filled nearly every canyon with moving ice, sculpting the landscape. Much evidence of this glaciation is lost to erosion and volcanic activity, but is still well-preserved today in the headwaters of the Little Deschutes River. Here one finds a classic U-shaped canyon, 1,500’ deep with moraines and a meandering stream, easily explored on a 2-mile trail (one way) and cross-country forays.

The very name “sphagnum bog” conjures up a vision of the Scottish moors — a dark, stagnate, acidic wetland with low fertility, tea-colored water and perhaps a well-preserved Iron Age bog body or two. But the misnamed Sphagnum Bog found just inside the west boundary of Crater Lake National Park is nothing of the sort. It’s actually a fen, fed by mineral-rich, alkaline spring water that supports a diversity of peat-adapted plants. A forested 2.3-mile trail leads to Sphagnum Bog, which can then be explored on a cross-country ramble.

Once a shallow 2,000-acre lake, which was filled by volcanic ash during the eruption of Mt. Mazama 7,700 years ago, Big Marsh today is one of the largest, high-elevation wetland/marshes in the nation. A half-hour drive west of Highway 97 from Crescent, it’s a one-of-a-kind resource supporting a wide diversity of Central Oregon wildlife — from elk, to river otters, to sandhill cranes — plus the largest population of threatened spotted frogs in Oregon. A 2.4-mile cross-country ramble invites visitors to explore this natural wonder.

Tucked away in a seldom-visited corner of Fremont-Winema National Forest, just a half-hour drive east of Highway 97 south of Crescent, is a collection of groundwater-fed fens (peat wetlands) supporting some of the richest concentrations of rare and distinctive plants in the Pacific Northwest. Formed in thick deposits of volcanic pumice from the eruption of Mt. Mazama 7,700 years ago, these fens are permanently wet year-round, with a fascinating assortment of mosses, sedges, wildflowers and even carnivorous plants.

What the heck are fens? Unlike bogs, which are acidic, low in nutrients and dominated by sphagnum moss, fens are fed by mineral-rich groundwater, creating neutral or alkaline peatlands with a rich diversity of brown mosses, sedges, wildflowers and even carnivorous plants. Along the east slopes of the Cascades in Central Oregon, fens are rare, occurring only between 4,500’-6,000’ in isolated perched aquifers over slow-draining glacial till from the last Ice Age. Two secluded but accessible fens can be found near Little Cultus Lake.

Sometimes the distinctive natural landforms of a place combine with centuries of human activity to create an exceptional mix of geography and history. The Klamath Marsh Narrows is such a place. This three-quarter mile crossing, in the midst of 65 square miles of sprawling marshland, has been used by Native Americans for millennia, by the John C. Fremont expedition in 1843, and by travelers down to the present day. It’s one of the best birding spots in Central Oregon, and hikers can follow in Fremont’s footsteps along the edge of the grasslands, enjoying solitude and sweeping Cascade mountain views.