scholarly journals Pollen Analysis of Glaciers in Special Relation to the Formation of Various Types of Glacier Bands

1949 ◽  
Vol 1 (06) ◽  
pp. 325-332 ◽  
Author(s):  
H. Godwin
Keyword(s):  
Pollen Analysis ◽  
Statistical Evidence ◽  
General Nature ◽  
Special Relation ◽  
New Approach ◽  
Flow Problems ◽  
Pollen Content ◽  
Glacier Ice ◽  
Glacier Flow ◽  
Different Parts

Abstract The author describes the work of Dr. V. Vareschi on the pollen content of glacier ice. A general account of the method of analysis is given. The results of statistical evidence of the analyses on several alpine glaciers are discussed, particularly in regard to the general nature of glacier flow in different parts of the glaciers. Vareschi’s suggestions as to the modes of origin of a certain type of ogive banding and of parallel banding (Pflugfurcheneis) are dealt with in the light of his findings. It is pointed out that what appears to be a valuable new approach to the solution of glacier flow problems needs elaboration before it can be accepted in all its bearings.

scholarly journals Pollen Analysis of Glaciers in Special Relation to the Formation of Various Types of Glacier Bands

1949 ◽  
Vol 1 (6) ◽  
pp. 325-332
Author(s):  
H. Godwin
Keyword(s):  
Pollen Analysis ◽  
Statistical Evidence ◽  
General Nature ◽  
Special Relation ◽  
New Approach ◽  
Flow Problems ◽  
Pollen Content ◽  
Glacier Ice ◽  
Glacier Flow ◽  
Different Parts

AbstractThe author describes the work of Dr. V. Vareschi on the pollen content of glacier ice. A general account of the method of analysis is given. The results of statistical evidence of the analyses on several alpine glaciers are discussed, particularly in regard to the general nature of glacier flow in different parts of the glaciers. Vareschi’s suggestions as to the modes of origin of a certain type of ogive banding and of parallel banding (Pflugfurcheneis) are dealt with in the light of his findings. It is pointed out that what appears to be a valuable new approach to the solution of glacier flow problems needs elaboration before it can be accepted in all its bearings.

A new approach to flow problems past a screen

1985 ◽  
Author(s):  
O. INOUE ◽  
K. KUWAHARA
Keyword(s):  
New Approach ◽  
Flow Problems

scholarly journals Crystal Orientation in Glacier and in Experimentally Deformed Ice

1960 ◽  
Vol 3 (27) ◽  
pp. 589-606 ◽  
Author(s):  
George P. Rigsby
Keyword(s):  
Crystal Orientation ◽  
Laboratory Experiments ◽  
Ice Crystals ◽  
Equal Area ◽  
Fine Grained ◽  
Planar Structures ◽  
Glacier Ice ◽  
Glacier Flow ◽  
High Shearing ◽  
Universal Stage

AbstractMore than 8,000 ice crystals have been oriented and measured for crystal fabric studies from widely separated temperate and polar glaciers, using a large universal stage and thin-section techniques. Very strong fabrics have been found and a number of laboratory experiments on deformation and recrystallization of ice were conducted in an attempt to solve some of the perplexing problems raised concerning glacier flow.In polar glaciers the c or optic axes of the ice crystals tend to be perpendicular to the foliation plane (alternating planar structures of bubbly and clear ice). In areas of high shearing stress the preferred orientation of the axes reached 39 per cent in 1 per cent of the area when plotted on a Schmidt equal-area projection. In temperate glaciers the optic axes tend to form three or four strong maxima which also appear related to the foliation.Patterns from ice deformed in the laboratory resemble some of the fabric patterns found in polar glaciers. During deformation of laboratory specimens, large crystals have been observed recrystallizing into many smaller ones, while fine-grained ice, after completion of deformation (both glacier ice and laboratory deformed ice), has been annealed at melting temperature into a few large crystals with different orientations from the original pattern.

scholarly journals Present dynamics and future prognosis of a slowly surging glacier

2011 ◽  
Vol 5 (1) ◽  
pp. 299-313 ◽  
Author(s):  
G. E. Flowers ◽  
N. Roux ◽  
S. Pimentel ◽  
C. G. Schoof
Keyword(s):  
Mass Balance ◽  
Force Balance ◽  
Surface Velocity ◽  
Internal Dynamic ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Ice Surface ◽  
Glacier Ice ◽  
Glacier Flow ◽  
Negative Balance

Abstract. Glacier surges are a well-known example of an internal dynamic oscillation whose occurrence is not a direct response to the external climate forcing, but whose character (i.e. period, amplitude, mechanism) may depend on the glacier's environmental or climate setting. We examine the dynamics of a small (∼5 km2) valley glacier in Yukon, Canada, where two previous surges have been photographically documented and an unusually slow surge is currently underway. To characterize the dynamics of the present surge, and to speculate on the future of this glacier, we employ a higher-order flowband model of ice dynamics with a regularized Coulomb-friction sliding law in both diagnostic and prognostic simulations. Diagnostic (force balance) calculations capture the measured ice-surface velocity profile only when non-zero basal water pressures are prescribed over the central region of the glacier, coincident with where evidence of the surge has been identified. This leads to sliding accounting for 50–100% of the total surface motion in this region. Prognostic simulations, where the glacier geometry evolves in response to a prescribed surface mass balance, reveal a significant role played by a bedrock ridge beneath the current equilibrium line of the glacier. Ice thickening occurs above the ridge in our simulations, until the net mass balance reaches sufficiently negative values. We suggest that the bedrock ridge may contribute to the propensity for surges in this glacier by promoting the development of the reservoir area during quiescence, and may permit surges to occur under more negative balance conditions than would otherwise be possible. Collectively, these results corroborate our interpretation of the current glacier flow regime as indicative of a slow surge that has been ongoing for some time, and support a relationship between surge incidence or character and the net mass balance. Our results also highlight the importance of glacier bed topography in controlling ice dynamics, as observed in many other glacier systems.

scholarly journals Creep-Velocity Bounds and Glacier-Flow Problems

1967 ◽  
Vol 6 (46) ◽  
pp. 479-488 ◽  
Author(s):  
Andrew C. Palmer
Keyword(s):  
Cross Sections ◽  
Upper And Lower Bounds ◽  
Steady Creep ◽  
Mean Velocity ◽  
Flow Problems ◽  
The Mean ◽  
Hand Calculation ◽  
Glacier Flow ◽  
Rate Relation ◽  
Creep Velocity

Abstract A general result due to Martin can be used to find upper and lower bounds on velocities in steady-creep problems. This method can be applied to glacier flow if ice can be assumed to satisfy a powerlaw stress–strain-rate relation. Bounds on the mean velocity over the glacier cross-section and on the mean velocity on the surface are determined for a particular example (a uniform parabolic channel, with powerlaw exponent 3) and they are shown to bound quite closely the exact solutions due to Nye. Bounds can be found rapidly by hand calculation. The method can be applied to real glacier cross-sections measured in the field.

scholarly journals Pollen-Analysis Investigation of a 20 m. Firn Pit on the Kesselwandferner (Ötztal Alps)

1966 ◽  
Vol 6 (44) ◽  
pp. 233-236 ◽  
Author(s):  
W. Ambach ◽  
S. Bortenschlager ◽  
H. Eisner
Keyword(s):  
Pollen Analysis ◽  
Mineral Dust ◽  
Late Summer ◽  
Dust Content ◽  
Analysis Methods ◽  
Deep Pit ◽  
Pollen Content ◽  
Small Pollen

AbstractFirn samples from a 20 m. deep pit were examined by pollen analysis methods in order to confirm the stratigraphy of the annual net accumulation back to 1949. The late summer horizon separates the overlying winter layer with a small pollen content from a firn layer with a large pollen content. There are also differences in the spectra of the species which enable a seasonal separation of the layers. In addition, the mineral dust content was examined.

A New Approach to Thin Aerofoil Theory

1951 ◽  
Vol 3 (3) ◽  
pp. 193-210 ◽  
Author(s):  
M.J. Lighthill
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Approximate Solutions ◽  
Radius Of Curvature ◽  
Two Dimensional ◽  
General Technique ◽  
New Approach ◽  
Flow Problems ◽  
Physical Problems ◽  
First Approximation

SummaryThe general technique for rendering approximate solutions to physical problems uniformly valid is here applied to the simplest form of the problem of correcting the theory of thin wings near a rounded leading edge. The flow investigated is two-dimensional, irrotational and incompressible, and therefore the results do not materially add to our already extensive knowledge of this subject, but the method, which is here satisfactorily checked against this knowledge, shows promise of extension to three-dimensional, and compressible, flow problems.The conclusion, in the problem studied here, is that the velocity field obtained by a straightforward expansion in powers of the disturbances, up to and including either the first or the second power, with coefficients functions of co-ordinates such that the leading edge is at the origin and the aerofoil chord is one of the axes, may be rendered a valid first approximation near the leading edge, as well as a valid first or second approximation away from it, if the whole field is shifted downstream parallel to the chord for a distance of half the leading edge radius of curvature ρL. It follows that the fluid speed on the aerofoil surface, as given on such a straightforward second approximation as a function of distance x along the chord, similarly is rendered uniformly valid (see equation (52)) if the part singular like x-1 is subtracted and the remainder is multiplied by .

scholarly journals Supraglacial Debris of G2 Glacier in Hidden Valley, Mukut Himal, Nepal

1979 ◽  
Vol 22 (87) ◽  
pp. 273-283 ◽  
Author(s):  
M. Nakawo
Keyword(s):  
Particle Size ◽  
Monsoon Season ◽  
Simple Relation ◽  
Laboratory Analysis ◽  
Field Investigations ◽  
Hidden Valley ◽  
Glacier Ice ◽  
Glacier Flow

AbstractField investigations of supraglacial debris were carried out during the monsoon season in 1974 on G2 glacier near Tukche Peak in Hidden Valley, Mukut Himal, Nepal. The thickness of the debris layer was observed to increase down-glacier. Laboratory analysis, however, showed a decrease in particle size in the same direction. This decrease is explained in terms of mixing of particles contained in glacier ice with the original debris as melting proceeds. A simple relation between debris mass and glacier flow is introduced to explain the observed results.

scholarly journals Some Comments on Glacier Flow

1950 ◽  
Vol 1 (07) ◽  
pp. 383-388 ◽  
Author(s):  
Richard Finsterwalder
Keyword(s):  
Shear Stress ◽  
Shear Plane ◽  
Critical Value ◽  
Ice Flow ◽  
Crystalline Materials ◽  
Fundamental Point ◽  
Glacier Ice ◽  
Slow Moving ◽  
Glacier Flow ◽  
Streaming Flow

Abstract Drs. Orowan and Perutz have shown that glacier ice does not behave as a viscous fluid but is plastic like all crystalline materials. The present author discusses two observed types of ice flow:—(1) the normal, regular streaming flow in slow-moving glaciers; (2) Block-Schollen * movement in swiftly flowing ice. Mention is made of the shear plane or laminar flow theory of Philipp. lt appears that Orowan s thesis is also applicable to Block-Schollen flow. The author agrees with Orowan on the fundamental point that when ice is subjected to shear stress a critical value of the shear stress exists beyond which the ice alters its consistency. But the author disagrees with Orowan in that he believes that below this critical value ice behaves as a viscous material, and he supports this view by reference to many phenomena, measurements and calculations.

A new computational method for the solution of flow problems of microstructured fluids. Part 2. Inhomogeneous shear flow of a suspension

1994 ◽  
Vol 262 ◽  
pp. 171-204 ◽  
Author(s):  
Andrew J. Szeri ◽  
L. Gary Leal
Keyword(s):  
Planck Equation ◽  
Orientation Distribution ◽  
Companion Paper ◽  
Computational Method ◽  
Flat Plates ◽  
New Approach ◽  
Flow Problems ◽  
Closure Approximations ◽  
Rigid Rod ◽  
Microstructured Fluids

A numerical investigation is conducted into the flow of a dilute suspension of rigid rod-like particles between parallel flat plates, driven by a uniform pressure gradient. The particles are assumed to be small relative to lengthscales of the flow with the effect that particle orientations evolve according to the local velocity gradient; the particles are also assumed to be small in an absolute sense, with the consequence that Brownian motions are of consequence. The calculations are performed using a novel approach, with a theoretical basis that has been developed previously in a companion paper (Szeri & Leal 1992). The new approach permits one to solve flow problems of microstructured fluids (such as suspensions, liquid crystals, polymer solutions and melts) without ‘pre-averaging’ or closure approximations. In the present work, the new approach is used to expose previously unknown pathological, non-physical predictions in various constitutive models derived using closure approximations. This appears to have passed unnoticed in prior work. In addition, the new approach is shown to possess several computational advantages. The determination of the orientation distribution of particles is self-adaptive; this leads, in effect, to a very efficient solution of the associated Smoluchowski (or Fokker–Planck) equation. Moreover, the new approach is highly suited to parallel (and vector) implementation on modern computers. These issues are explored in detail in the context of the example flow.

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