The Bomber Traverse Map

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The Bomber Traverse is an informal hut-to-hut wilderness backpacking route in the Talkeetna Mountains of Alaska. The purpose of the Bomber Traverse Map is to aid wilderness travel by indicating general backcountry routes and hut locations, by codifying locally-accepted names for peaks and other features, and by documenting rapid changes in glaciation.

Download the Bomber Traverse Map

The Bomber Traverse Map is available for free under a Creative Commons CC BY-NC-ND 3.0 license. This means that you can copy, use and share the map at no cost, but cannot distribute alterations or sell it.

The Bomber Traverse Map was created at a size of 18×24″. You can also print the map at 11×17″, but text will be smaller so try to print at the highest resolution possible. Waterpoof paper can be purchased online and is preferable to uncoated paper or lamination for trail maps. Alternately, you can download and save the file for use on a mobile device.

Current Edition: 1.3, 51mb PNG file

Click Here to View and Download

Background

In August 2012 a group of four hikers, including myself, set out from the MCA Rainery (Mint) Hut to climb Bombardment Pass, cross Penny Royal and Bomber Glaciers, and return to our cars via the Reed Lakes trail. We planned to climb over an alpine pass between Penny Royal Glacier and Bomber Glacier known as “Bomber in a Day Gap” because it allows a truncated version of the Bomber Traverse that can be completed faster than the entire trip. When we set out we expected a challenge: the Traverse climbs tall, teetering boulder fields and crosses glaciers. We weren’t expecting our maps to lead us–literally–off a cliff.

We crossed Penny Royal Glacier in a flurry of August snow, and scrambled to the top of the rocky pass leading to Bomber Glacier. On the current USGS maps, this pass appeared as a shallow ribbon of rock between the two sweeping masses of Penny Royal and Bomber Glaciers. But as we climbed down toward Bomber Glacier, we realized something was wrong. The terrain rolled over more and more steeply, and we found ourselves threading around steep ledges of glacier-carved granite. The scree was loose, wet, and covered in slippery snow.

Descending “Bomber in a Day Gap,” Ryan Kenny in the foreground.

Just a few dozen feet above Bomber Glacier, disaster nearly struck. One of our group slipped, tumbled down the rocky face, bounced over a deep randkluft (a crevasse-like feature formed when the top of a glacier melts away form the rock headwall behind it) and landed on the glacier. She was unhurt but shaken, and after we made sure everyone was safe we asked the unavoidable question:

Where the %&$#?@ did this cliff come from?

A look at the USGS maps and the surrounding terrain features provided the answer: the glaciers had receded. And not just a little bit, but dramatically. Bomber Glacier, which we were now standing on, had lost about a third of its length since the current maps were made, and likely well over a hundred feet of depth. The cliffs we had struggled down had always been there, but until recently they’d been hidden under glacial ice.

Glacial recession in the Talkeetna Mountains is more than a collection of abstract scientific data points. Our experience in 2012 demonstrated that for Alaska outdoorspeople, deglaciation is a practical issue with major implications for safe travel. The Bomber Traverse Map was created primarily to communicate the effects and importance of glacial change so that backpackers can move more capably through this remote wilderness area.

The Bomber Traverse Map – The Basics

The Bomber Traverse Map is made up of six merged quads of the 2016 USGS 7.5-minute maps, with additional data overlaid onto them. I chose the boundaries of the map by tracing the tops of the ridgelines surrounding the Bomber Traverse; the resulting map should allow a backpacker to identify every mountain visible from the traverse, with the exception of those far down Bartholf Creek or back down Palmer-Fishook Road.

The 2016 USGS maps were used because their elevation data seems more accurate than previous maps, and includes topographic changes caused by glacial recession. However, the 2016 maps provide their own challenges: many permanent lakes that had been included in older USGS maps are missing, as are many man-made landmarks such as old mine sites and buildings. And while the 2016 maps do contain more accurate representations of glaciers in their current states, they are already somewhat outdated and some glaciers–such as the large, crevasse-riddled Wintergreen Glacier–are missing entirely.

The Bomber Traverse Map therefore attempts to improve upon the 2016 maps both by adding additional information and by correcting clear mistakes.

Mapping Glacial Recession in the Talkeetna Mountains

The topographic data (including glacier boundaries) compiled in the 1950s was used on USGS maps without apparent updates until at least 1994. As of this writing in 2017, many mapping applications (including smartphone apps like Gaia GPS) continue to use this data as a base layer. The Bomber Traverse Map overlays the glacial boundaries recorded around 1950 onto the 2016 maps (and adds glaciers missing from the 2016 maps).

Example of glacial recession mapping. On the left is the 1950’s USGS maps, showing a 1.4-mile-long glacier between Triplemint Spire and Telemint. In the middle is the 2016 USGS map, indicating a much smaller glacier. On the right is Edition 1.1 of the Bomber Traverse Map, which overlays the glacier outline from the 1950’s maps onto the 2016 map, emphasizes the boundary of the glacier on the 2016 map, and adds place names.

Glaciers that appear on the 1950s maps but do not appear on the 2016 maps are marked with a red “X” to indicate that they have apparently disappeared.

Practical Implications of Glacial Recession

Why not simply show the most accurate current glacial boundaries? Why indicate the historical extent of glaciers at all?

Understanding glacial change is important for backpackers much the way that knowing historical low-tide and high-tide water levels might be important for a boat captain. It allows backpackers to better avoid hazards, anticipate terrain, and navigate through a rapidly-changing environment.

As we experienced on our hike over Bomber in a Day Gap in 2012, a glacier in recession is more likely to uncover steep or dangerous terrain that is not yet reflected on any maps. A cliff of only ten to twenty feet can create a significant hazard. Many glaciers in the Talkeetnas have lost at least ten times this much ice since the 1950s maps were published.

Rock that has recently emerged from under glaciers can be challenging to move through because it has not had time to settle and stabilize. This is true of moraines left at the retreating front edge of a glacier, but it is especially true of loose rock at a glacier’s headwall. In many glacial cirques in the Talkeetnas rock has fallen from mountainsides, piled up and fanned out onto the top of glaciers. Because the foundation of these piles is a shrinking glacier, these rock fans do not have the chance to settle at all and can be very unnerving to ascend. One prominent example is the rock fan on the northeast side of Bomber Pass, which rests on the top of Bomber Glacier.

Brett Frazer and Tim Treuer stand in the midst of a recently-glaciated valley below Montana Peak. Retreating glaciers in the Talkeetnas leave behind piles of loose boulders and rock that can be challenging to travel through.

Receding glaciers have left behind many small lakes, moraines, and other features that have implications for backcountry navigation. For example, no maps currently in use show the small lake forming off the nose of Snowbird Glacier, to the northwest of the Snowbird Hut. Knowing the rate of glacial recession gives a backpacker a better frame of reference when encountering unexpected terrain.

Local Names

Only a few of the tallest peaks and most historically-significant drainages in the Talkeetna mountains carry “official” names recognized on USGS maps. But the mountains, lakes, and other land forms are too close to Alaska’s population centers and too heavily visited to remain nameless. Over the last several decades, local names for many land features have gained broad (if not totally unanimous) acceptance. Codifying place names allows backcountry users to refer to land features with consistency and clarity, improving logistics and safety.

To determine place names for the Bomber Traverse Map I referred to handwritten maps left at the Snowbird, Bomber and Rainey (Mint) Huts and to online and personal maps maintained by well-known Alaska outdoorspeople. When there was a conflict between maps, I reached out to map authors and consulted satellite imagery, USGS maps, members of the outdoor community.

Some maps contained conflicting information that could not be reconciled. For example, the handwritten map at the Snowbird Hut put “Nevada Peak” north of Gnome Lake, where other maps put that name on another peak many miles away, just south of Telemint Glacier. The most common conflict with names simply occurred with spelling. Take, for example, the prominent peak directly north of the Bomber Hut. Maps variously spelled the name of this peak “Neltura,” “Nalteni,” and “Nelteni.” According to several sources, this peak was named after the indigenous Dena’ina word for “Thunder”. I consulted a Dena’ina dictionary and found that “Nelteni” seems to be the correct spelling.

From left to right: 1) Handwritten map in the Rainery (Mint) Hut, 2) Handwritten map in the Snowbird Hut, 3) William Finley’s online map, 4) Steve Gruhn’s map, 5) The Bomber Traverse Map, ed. 1.2. Note the different spellings of both Nelteni and Teni Weni.

Determining place names requires judgment and discretion. Ultimately, the names we give places are arbitrary and imposed. Places can have many names, one name, changing names, or no name at all. Most peaks, valleys, and streams in the Talkeetna Mountains remain nameless, and in this vast and little-tracked wilderness area that seems appropriate. If you believe I have made an error or would like to make a suggestion for future editions of the Bomber Traverse Map, please get in touch.

The Bomber Traverse Route

The Bomber Traverse is an informal, unofficial route through the Talkeetna Mountains wilderness. It is not a trail, and is not signed, maintained, or defined by any organization. The Traverse winds around cliff bands and over boulder fields, and crosses at least two glaciers with constantly-changing surface hazards. There is no single best way to complete the Traverse, and the optimal route changes with the conditions. Glacial recession may cause the optimal routes to change significantly over the coming decades.

The routes indicated on the Bomber Traverse Map are based on online research, personal experience, and GPS tracks from myself and others. I’ve tried to place the route on what I believe is the safest, easiest way through this wilderness area. However, users should always react to the conditions and rely on their own judgment in order to stay safe.

Note that the Bomber Traverse Map shows summer route. Winter routes will necessarily be different, especially because they must consider avalanche risks.

Route changes from the Bomber Traverse Map between editions 1.1 (left) and 1.2 (right). The route in edition 1.2 avoids the steep, slippery cascade below Snowbird Glacier, and leads backpackers down the Bartholf Creek drainage on shallower terrain. These changes were made after a boots-on-the-ground trip in August 2017.

Bomber Traverse Huts

The Bomber Traverse Map includes markers and GPS coordinates for the AAC Snowbird, MCA Rainery (Mint), and MCA Bomber Huts. Current information about the huts can be found on the American Alpine Club and Mountaineering Club of Alaska websites.

I did not include the MCA Dnigi Hut on the Bomber Traverse Map. Though the Dnigi Hut was originally intended to be part of the traverse, it is rarely visited during the summer months because access is somewhat difficult and unintuitive. There have been recent proposals to burn down or relocate the Dnigi Hut and its future, at best, is uncertain.

The Mint Hut, surrounded by the Talkeetna Mountains of Alaska

The Mint Hut, with Doublemint, Peppermint, and Triplemint Spires in the background. The Bomber Traverse huts are maintained entirely through volunteer efforts and donations. If you plan on using them, please donate or sign up for membership with the Mountaineering Club of Alaska and the American Alpine Club. Please treat the huts respectfully and clean them thoroughly when you leave so that they’re ready for the next group!

Map Editions

  • Edition 1.3 – 51MB PNG – Added names (Snowbird Village Site, Lane Hut Site, the Monolith, Kendalmint, Tenemint). Added relief shading. Corrected mistake on legend re: glacier boundaries. Thanks to Fred Trimble for creating the relief shading layer, suggesting new ways to distribute digitally, and providing additional place names.
  • Edition 1.2 – 36MB PNG – Changed names (Didilkama to Didilkama Peak, Yisba to Yisbo Peak, Lower Spire to Lower Tower, Teeny Weeny to Teni Weni, 3-Bell Spire to Three Bell Spire). Added names (Friendship Pass, Rae-Wallace, Black Prospect, Marmot, Peak 4068). Updated glacier boundaries (Wintergreen Glacier, unnamed glacier remnant above Upper Reed Lake). Moved peak locations (Yisbo Peak). Improved Bomber Traverse routes (Snowbird Hut to Bomber Hut, Bomber Hut to Bomber Pass). Removed notes about deficiencies in USGS maps–glaciers mistakenly omitted from 2016 maps are added in without notation. Slight changes to terrain notes and map legend. Thanks to Bretwood “Hig” Higman, Lang VanDommelen, Steve Gruhn, and William Finley for their assistance in reviewing Edition 1.1 and suggesting improvements for Edition 1.2.
  • Edition 1.1 – 36MB PNG
Tim Treuer carrying the Bomber Traverse Map in a backpack

Tim Treuer carrying a laminated first edition of the Bomber Traverse Map to the Snowbird Hut, August 2017.