By Robin Mayo
​
If you are looking for an adventure that is within reach and family friendly, I highly recommend planning a trip to the Castner Glacier Ice Cave.  With a two-hour drive from Glennallen and a one-mile walk, you can access a truly breathtaking experience. 
The cave is approximately 50 feet wide and 40 feet tall at the entrance, and tapers as it goes back about 200 feet into the glacier. (Note:  these numbers are pure estimate, I’m wishing I’d done some pacing!) Part of the floor is smooth ice, and the rest a mix of ice, dirt and rocks.  We followed the curving cave until it was pitch dark, and the ceiling was too low for walking.  Best of all, it seems to be pretty stable in the winter, so it can be explored in relative safety if basic precautions are followed.
One of the surprises for me was how many other people were there!  On a December weekend we saw about 40 other people on the trails and at the cave, and I’d estimate there were over 100 on a weekday during the holiday break.  It was fun to see so many people respectfully sharing the trails and enjoying themselves, but if you want to experience the place in solitude you may need to choose a weekday and/or be prepared to wait patiently.
Near the entrance, the ice was shining, with a unique scalloped texture and run through with ribbons of gravel reminiscent of  polished marble.  Further in, the ceiling is festooned with ice crystals, some reminding us of perching butterflies, and others needle-sharp or feathery.  We could hear water gurgling beneath the ice, and a few damp spots reminded us to be very cautious.
The cave is accessed from the Castner Creek Bridge at mile 217.3 Richardson Highway, about 20 miles north of Summit Lake. Two trails go to the east up the creek, one from the parking area at the southeast corner, and the other about 100 feet north of the bridge.  DOT has made crude but usable parking areas around the bridge.  At my last visit in early January both trails were beautifully hard packed and easily walked.  About halfway to the cave they come together on the creek. The trails are mostly similar and both well used, but the southern one included a steep 15 foot drop down to the creek, and the northern one is partly in the woods so more sheltered.
If you go, I’d recommend checking the weather for Delta Junction and Paxson to get some idea of conditions.  This is a notoriously windy area, so come prepared with extra layers for the wind chill.  I’d also recommend having snowshoes or skiis available in case the trail is blown in, which was the case on my first visit in December. 
Although this is a relatively easy adventure, please have safety in mind.  There was no cell phone coverage, so someone should know where you are and when you plan to return.  Much of the trail is on an active creek, so give open leads a wide berth and be alert for new holes, which could open up even in the trail.  At the cave, you may want walking sticks and/or cleats for your boots to make it safer to walk on the ice.  There are rocks suspended in the ice which could fall, especially as the weather gets warmer.  And towards the back of the cave, we could hear water and saw evidence of recently overflow and seepage, so be very cautious on the ice. If you want to explore the very back of the cave you will need a flashlight or headlamp, which we also found very useful for getting good photographs. Families with young children might want to bring along a sled for taxi service for tired little explorers.
Although this place feels like the middle of nowhere, it is important to be prepared for and considerate of other visitors. The parking areas are small, but workable if people don’t hog space, and are careful not to block other vehicles.  Lots of dogs were enjoying the adventure, but everyone had leashes and was keeping their pet close, which I appreciated.  The walk is so short a snowmachine would be needed only for someone who couldn’t make it otherwise.  If you do bring your machine please yield to foot traffic, who have the right of way. In a place like this, it is also courteous to stay on the trail as much as possible, to keep the views pristine and also avoid creating lots of side trails which make the main trail hard to follow.
I wish I knew more about the history and geology of this cave, which appears to be formed from the combination of the stream running underneath, and the warm summer air melting out the entrance.  It sounds like it has been there for quite a few years.  The mouth of the cave faces roughly northward, which means it is spared long exposure to the sun which would speed up the melting.  WISE is considering leading some hikes there later in the winter, if you are interested please let me know and I’ll fill you in on details, or keep an eye on the WISE FB page and website.

Copper River Record  February 1, 2018
By Robin Mayo
On Wednesday, January 17, 27 people gathered at the Wrangell-St. Elias Visitor Center for a talk by Prof. Andreas Pflitsch on his work in Cave Climatology.  The first slide of his presentation showed a subway tunnel, and Prof. Pflitsch explained that he first worked in North American “caves” as a consultant for the city of New York, providing information on the airflow patterns in subway tunnels to help them plan for possible terrorist attacks. 
Prof. Pflitsch is a professor at Ruhr University, Bochum, Germany, Department of Geography, Climatology of Extreme Environments.  He joked that he earns his money in urban caves, such as subways, and spends it in wild caves.  His underground resume includes Boulder Caves on Mt. Washington, New Hampshire, barometric driven caves in South Dakota and New Mexico, and ice and glacier caves in the Pacific Northwest, Alaska, and Mauna Loa, Hawaii.  What they all have in common are unpredictable, dynamic climates which are extremely challenging to study.
Prof. Pflitsch made note of the difference between ice caves, which are rock caves which contain perennial ice, and glacier caves which are in or directly under glaciers.
The first place we visited was Frosty Cave, an ice cave near Kennecott Glacier.  This relatively small system consists of three rooms, connected to each other and the outdoors by small passages.  Data from temperature sensors showed the climate inside the cave fairly stable, mostly below freezing, with seasonal cycles that lag behind the actual seasons.  But there were also curious exceptions to the patterns, leading to theories that there may be so-far undiscovered chimneys and passageways affecting the climate inside the caves.  For example, a chimney opening to the outdoors may make the system active, drawing in warm air downwards in the springtime and summer, and flushing warm air up and out in the fall and winter.  When Prof. Pflitsch lamented that he can visit the cave only once a year and is limited in the instruments he can deploy, an audience member raised his hand, asked for the coordinates, and offered to visit once a week with fresh batteries!
Also in Wrangell-St. Elias National Park, the Fosse Pothole is a 150  foot deep cavern which holds many mysteries.  It is not affected by cold snaps as dramatically as Frosty, and the summer temperatures are very stable.  “This is Science,” exclaimed Pflitsch, “you can have a PhD but you will never know everything!”
The speaker then introduced Brent MacGregor, a caver and co-leader of the Pacific Northwest group Glacier Cave Explorers.  While doing research for a book on caves in Oregon, Brent heard rumors of dramatic caves under glaciers on Oregon mountains.  It was challenging finding people to explore with him, because in general cavers don’t have high altitude experience, and mountaineers have learned to avoid glaciers as they are hazardous.  But he did eventually find what he was looking for in Sandy Glacier on Mt. Hood, Crater Glacier on Mt. St. Helens, and Fumarole Caves in the Ice Cap on Mt. Rainier.
In Sandy Glacier, MacGregor and his team explored a network of caves they named Snow Dragon, Pure Imagination, and Frozen Minotaur.  At the back of Pure Imagination, they found a glacier cave which defied explanation, as the air temperature was 7C (about 45 degrees F.) They named the cave Hot Imagination.  At a Cave Science Conference when many attendees were questioning the accuracy of the figure, Brent met Professor Pflitsch, who had seen enough anomalies in caves to trust the numbers, and wanted to go help find an explanation.
With teams of explorers and scientists, the two have made many expeditions in the Pacific Northwest, and we were treated to spectacular photos and some great stories.  It took a thermal camera to solve the mystery of Hot Imagination.  They discovered multiple warm springs inside the cave, where volcano heated water mixed with glacial meltwater, significantly warming the interior of the cave.  With this infusion of warmth, Sandy Glacier is receding, and the caves are quickly disappearing.
At the summit of Mt. Rainier, the team explored a complex of caves around the interior rim of the crater, which were also warmed by the volcano.  These caves are actually warmest in winter, when snow cover blocks the entrances, and fumaroles with temperatures up to 110F warm the air.
Next, Prof. Pflitsch took us to the volcanic crater at the summit of Mt. St. Helens, where the only growing glacier in the lower 48 is located. It is a desolate landscape, with no stable ground, everything new, movement everywhere.  Asked about the danger, Prof. Pflitsch noted the dangers we face every day doing things like driving cars.  “The only thing that bothered me was wet socks.  For the next expedition, new socks every day!”
Finally, he gave a quick explanation of his work in the highway tunnel in Keystone Canyon.  He first studied the cave when both ends were nearly blocked off, and it was a fascinating (and for a change, easily accessible) study in the steadiness of year-round climate of a closed system.  Then the “Damalanche” of 2014 sent water blasting through the cave, and everything changed.  Now open at both ends, it is a totally different system where the temperature fluctuates with the days and seasons.
On the subject of climate change, he was careful to note that none of his data spans a long enough time to be meaningful for studying long-term trends.  He hopes to continue to establish recording programs in caves to start to build a large data set. 
The entire evening was a celebration of exploration and inquiry, and Prof. Pflitsch encouraged everyone to follow their curiosity:  “A scientist is someone who is doing research.  You don’t need a PhD to make real science!”

​Prof. Andreas Pflitsch at Pu'u O'o of Kilauea, Big Island, Hawaii.  Photo by Michael Killing-Heinze