Seen from space, the Himalayas are a white fence separating the red Tibetan plateau from the brown plains of India. The posts in this fence are the 8000 m peaks, mountains like Kanchenjunga, Makalu, Chomolungma-Lhotse, Cho Oyu, and Shishipangma. These granite monsters protrude thousands of meters above the little mountains around them. Yet you could hide Denali, North America's biggest mountain, inside these little mountains. If you are into mountains, whether as a climber, a mystic, or as a scientist, this is the place.

Why It's Interesting
The Himalayas are a frontier region for science. Because of their remoteness and extreme altitude, only in recent times have scientists started doing research there. Because the collision between India and Asia is ongoing, geologists use the Himalaya as a laboratory for studying how continental collisions generate mountains.

My interests in the Himalayas are more applied. These mountains and the plateau behind them play a crucial, yet dimly understood role in the planet's climate. In summer, solar heating of the Tibetan Plateau sets up a giant convection cell that draws the monsoon inland from the sea. The monsoon brings rain, which waters the crops, which feed most of the world's people. The monsoon, as Mallory and Irvine knew well, also brings the snow to the high Himalayas. Glaciers there advance and retreat in response to variations in the amount of this snowfall. We know surprisingly little about natural variations in the strength of the south Asian monsoon. By studying the timing and extent of glacier fluctuations over the last 5000 years, we can learn about the long term, natural variability of the monsoon.

What I Do
To reconstruct the history of the monsoon I need chronologies of glacier advance and retreat. This means dating glacial moraines, the elongate heaps of gravel that glaciers deposit along their margins. To date a moraine you must find stratigraphic sections - places where stream erosion or landslides expose the moraine's interior. There you look for soils that the glacier overrode or for debris (trees, yaks) it bulldozed up in its advance. I then radiocarbon date the organic debris to determine moraine age. Common materials used for dating include plants, snails, and bones - anything that once inhaled carbon dioxide. Briefly, I grub around in piles of dirt looking for pieces of dead things.

Another source for a glacial chronology is a sediment core from a lake that receives glacial meltwater. When a glacier is nearby, the lake turns into a settling pond choked with sand and silt. When the glacier retreats, less silt goes into the lake, the water clears, and algae grow. All this shows up in cores we take through the lake ice with an apparatus that resembles an eight-foot long plumber's helper. Another source for a glacier chronology comes from the annual rings of mountain trees. Narrow rings record reduced growth caused by mechanical disturbance or lowered temperature caused by a glacier nearby. You can either cut the tree down and remove a cross-section disk or, and this is better because it doesn't harm the tree, remove a thin core with a tree borer.

Remoteness makes the work challenging. But the worst thing is that above 6000 m you have trouble thinking. Try counting backwards by 13s from 408 while running a six minute mile - it's the same sensation. It's best to stay near base camp for the first few weeks. Once the danger of acute mountain sickness is past, and after I find out from the Sherpas what the locals are up to (religious taboos? bandits?), I start hiking around. This is field science. Everything is on foot. At 18,000 feet it takes three weeks before you can work all day. Eric's expeditions usually last two months. So I'm left with about one month to work before its time to leave.

The Plan in '99
The 1999 Spring expedition will be my third research trip to the Himalaya. In 1991, I was on the North side of Everest with Eric and the AFFIMER Expedition. I gathered enough scientific data to write a scientific paper on the glacial geology of the Rongbuk Valley. In 1996, I accompanied Eric on a trip to Cho Oyu and discovered a lot of interesting glacial deposits. I am still working on the write-up from that trip. Last Fall I did a reconnaissance of the south side of Everest, an area I hope to return to next autumn. The grand scheme is to visit all sides of Everest. This isn't just tourism. Because of the mountain's rain-shadow effect, we suspect that the glaciers on the different sides of the mountain are responding to different climatic signals.

This Spring I'll be working mainly in the Kharta Valley northeast of Everest. This valley was visited by the early British expeditions who, without maps, were trying to find an easy approach to the north side of Everest. The Kharta Valley turned out to be a hard way to reach the mountain. It is perfect for me because it is relatively low in altitude, has trees for tree-ring analysis, has lakes for coring, and contains a large variety of moraines.

I'll be accompanied by Passang Tsering who is from Khumjung, a Sherpa village in Nepal on the south side of Everest. Passang is 24 years old and speaks fluent English and Japanese. Besides having a strong back and quick mind, Passang can translate for us. For part of the time we'll be joined by Bernhard Rabus, a German glaciologist and physicist with the German Space Agency in Munich. Though he is very interested in the Yeti, Bernhard's real specialty is glacier-climate interaction. He is also expert with remote sensing techniques. We hope to use satellite-based radar to map snowlines throughout the Everest region to test for correlations between snowline altitudes and monsoon intensity. That's the plan. We will see what happens. Due to late start with preparations, we still lack money for Rabus's overland expenses, about $3000.

—Dan Mann, Expedition Scientist