- Velocity: The modeled Flubber velocity is similar to
"real" valley and piedmont glaciers - flow is fastest at the surface
and along the centerline where basal and lateral drag is minimal. In
addition, experimentation revealed that surface slope controls velocity,
just as with real glaciers. Since we did not model the surging characteristic
of the Malaspina, our resultant velocities are more typical of the quiescent
stage when internal ice deformation dominates flow.
- Contoured moraines: The folded pattern along the left-hand
piedmont wall in the Flubber model (circled in the left-hand figure below)
resembles the location and orientation of a V-shaped moraine on the western
side of the Seward Valley mouth (circled on the right-hand figure below).
A similarly oriented fold is visible on the right-hand side of the
Flubber piedmont. It is possible that the likeness between the Flubber
and the Malaspina is a coincidence, but the strong similarity between the
two suggests that it is a result of side shear induced by a lateral gradient
in longitudinal velocity. In general, however, the lateral folding
of "moraines" in the Flubber model have a different orientation than those
observed on the eastern margin of the Malaspina (see figures below). Thus,
we were unable to reproduce the characteristic contoured moraine pattern
of the Malaspina Glacier. This may indicate that the contoured
moraines are indeed created by glacier surging. However, it is difficult
to make this conclusion given the fundamental differences between our model
and the real Malaspina.
- Fundamental differences between the
Flubber model and the Malaspina:
- Dimensions: Our model
dimensions are not directly proportional to those of the Malaspina. The
ratio between the valley width and the piedmont width in the Malaspina is
1:16 vs. 1:3 in our model. The slope and orientation of valley walls
for our model were chosen based on logistical constraints, as a properly proportioned
model would require a ~2 m wide piedmont and an unmanageable volume of Flubber.
- Coupling between Flubber and the
bed and walls: The Malaspina is a surge-type glacier which
requires some degree of basal sliding. The Flubber, on the other hand, was
completely coupled with both the bed and side walls. This caused overturning
of the Flubber at the toe - a process that does not occur on the Malaspina.
- No ablation: The
Malaspina Piedmont Glacier reaches an elevation of 20 masl at its seaward
extent, which is well below the local 2100 meter snowline. The Malaspina
does not have a calving margin at its present extent, and thus melting is
the primary ablation process. We did not attempt to model ablation
because we could not realistically model surface melting with Flubber.
- Inadequate ice reservoir:
To supply our model with a constant source of mass, a large volume of Flubber
was placed in a "reservoir" at the glacier "headwall". This is not
a realistic scenario, since real-world ice accumulation is integrated over
the glacier's surface. Instead, a "kinematic wave" was produced in
our model - the larger mass moved down-glacier at a faster rate.
- Side wall characteristics: Bordering
the main (Seward) lobe of the Malaspina piedmont are dynamic glacier lobes
(Agassiz and Turner) that undoubtedly affect the folding patterns seen especially
on the eastern margin. It is possible that we could not replicate these
complex folds because our "piedmont walls" are stationary.
- Initial orientation of moraines:
The Malaspina moraines are lateral moraines that develop through accumulation
of debris from erosion of adjacent mountains. In our Flubber model, the
colored bands were initially transverse to the valley axis, and became parallel
to the walls only after considerable stretching and thinning. It is
interesting that the final orientation of colored Flubber bands resembles
that of lateral moraines.
- Future Attempts:
- Induce surge-type behavior by injecting water at the base.
- Create a model with dimensions proportional to the Malaspina.
- Impose disruptions on the lateral margins to see if they
propagate and produce Malaspina-type folds.
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