I had some time to look in the US Geological Survey website,
and found that indeed the consensus is that Lake Baikal is a rift, based on
seismic reflection and seismic refractions surveys. It even has a small
hydrothermal vent somewhere in the southern portion. It would have to be a very
young rift, however, because of the match in the geology of both banks, the
fact that the lithosphere has not thinned considerably, and the fact that “the
crack” is 1,637 m deep and the super steep slope has not failed. Seismic
reflection shows a wedge of sediments, nearly 1,000 m thick at the base of “the
crack”, which has led some sedimentologists to speculate that it would take
several million years for such a great thickness of sediments to accumulate (I
suspect that one or two submarine landslides in such a narrow basin would be
enough to deposit such thickness as debris flows). I need to look into this in
more detail once I am home.
Our morning activity was going to include a boat ride in the
lake, a treat that we were all looking forward to. The morning was cool, and
there was a good wind blowing, so I could well imagine myself as an intrepid
explorer braving the elements on the stern of the Icebreaker Angara. Ah, but
they had not said a ship ride, had they? When we got to the shore we found out
that the ride was going to be in tow tiny outboard boats. Suddenly the waves
looked enormous compared to the side of the cockleshells we were going to
venture in. To add to the excitement our young pilots thought it was extremely
fun to pretend they were driving speed boats, and gleefully shot themselves
like arrows at the incoming waves. It was exhilarating, but I for one ended the
rise slopping wet. We had a great view of the southern shore of the lake,
however, as well as of the considerable mountain masses that form its shores.
At lunch we had a delicious serving of fish and potatoes,
and that made me think that so far the people, food, and towns we have found
are very European in aspect and origin. We are very close to the border with
Mongolia, so I would have expected at least some Asiatic influence.
After dinner we boarded a couple of vehicles, and headed
west to the Tunkinsky National Park, where we will spend three nights. I now
really feel that we are getting closer and closer to Mongolia, in the direction
of the Altai Mountains. Oh, look, there is a small Buddhist temple! Actually,
some of the folks here combine the Buddhist rituals with older shamanic
beliefs, and the temple is adorned gaily with thousands of ribbons tied to the
trees, each a prayer for a special favor or simply for the well being of the
community and the world.
In the distance we see three tiny hills, set against a
background of jagged peaks. Our driver described them as volcanoes, and that
reminded me of the small basaltic cinder cone I saw with Zoe and John in
Mongolia last summer. More about these small volcanoes tomorrow.
We arrived at the small town of Arshan, which will be our
center of operations, around 5 pm, and like the good group of Germans we are
made an emergency stop at the local supermarket to load on beer and vodka. We
might suffer hunger and exhaustion, but we shall never suffer from thirst!
There is a small river running through the town, with a
channel that has been obviously excavated and straightened. The abundance of
big boulders bespeaks of a channel that with severe rain turns into a raging
torrent and the venue for destructive debris flows. As it happens, the guest
house we are staying in is located right against the bank of this channel, so it
is a good thing that we have had a glorious sunny day.
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