periglacial activity along an elevational gradient of gloria sites, white ...
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Periglacial Activity Along <strong>an</strong>Elevational Gradient <strong>of</strong> GLORIA SitesWhite Mountains CaliforniaGinger L. Schmid<strong>an</strong>dForrest D. WilkersonDepartment <strong>of</strong> Geography―Minnesota State University, M<strong>an</strong>kato
Periglacial Activity Along <strong>an</strong> Elevational Gradient<strong>of</strong> GLORIA Sites, White Mountains California1. GLORIA Background2. Study Sites3. Relict <strong>an</strong>d Active L<strong>an</strong>dforms4. Periglacial Measurementsa. Vertical Heaveb. Horizontal Surface Movement
GLOBAL OBSERVATION RESEARCH INITIATIVE IN ALPINE ENVIRONMENTShttp://www.<strong>gloria</strong>.ac.at/
GLOBAL OBSERVATION RESEARCH INITIATIVE IN ALPINE ENVIRONMENTSGLORIA Purpose:“…to establish <strong>an</strong>d maintain a world-widelong-term observation networkin alpine environments…”
GLOBAL OBSERVATION RESEARCH INITIATIVE IN ALPINE ENVIRONMENTSGLORIA Purpose:“…The data will be used to assess <strong>an</strong>d predictlosses in biodiversity <strong>an</strong>d other threats to thesefragile alpine ecosystems which are underaccelerating climate ch<strong>an</strong>ge pressures.”
GLOBAL OBSERVATION RESEARCH INITIATIVE IN ALPINE ENVIRONMENTSGLORIA Master Sites:“In parallel to the globally applied Multi-Summitapproach, the GLORIA network aims toestablish so-called Master Sites.”Mount Schr<strong>an</strong>kogelAustria, 1994WMRS-GLORIAU.S., 2006
GLOBAL OBSERVATION RESEARCH INITIATIVE IN ALPINE ENVIRONMENTSGLORIA Master Sites:“In parallel to the globally applied Multi-Summitapproach, the GLORIA network aims toestablish so-called Master Sites.”Mount Schr<strong>an</strong>kogelAustria, 1994WMRS-GLORIAU.S., 2006
White Mountains
Location <strong>of</strong>Long-Term (1991-2008)Periglacial Study SitesWhite Mountain Peak• Highest rates <strong>of</strong><strong>activity</strong>Mount Barcr<strong>of</strong>t• Most intenselymeasured sitePiute <strong>an</strong>d Sheep Mtns• Limited <strong>activity</strong>(elevation <strong>an</strong>d lithology)Sage Hen Flat (2005)• Horizontal surfacemovement only
Absence <strong>an</strong>d Presence <strong>of</strong> Periglacial SortingReed Dolomite ― Campito S<strong>an</strong>dstone
PeriglacialL<strong>an</strong>dformsEffect <strong>of</strong>Slope AngleonSorted Patterns
Inactive L<strong>an</strong>dformsRelict Polygons Sheep Mountain Saddle (Campito S<strong>an</strong>dstone)
Inactive L<strong>an</strong>dforms: Nets <strong>an</strong>d Stripes
Inactive L<strong>an</strong>dformsRelict sorted circles at Piute Mountain siteSorted stripes are visible on the slope in the background
Relict polygons, East Shield site near McAfee NRA
Relict polygons East Shield Gr<strong>an</strong>odiorite (3550m)
Mount Barcr<strong>of</strong>t Relict Polygons <strong>an</strong>d Active Frost Boils(3900m)
Plateau Site Active Frost Heave (4050m)
Active <strong>periglacial</strong> sorting at White Mountain Peak site.The GLORIA site is out <strong>of</strong> the photo upslope to the right.Photo is taken looking up‐slope at the road.
Summit Slope Movement (4180m)Two YearsSix Years
Summit SitePeriglacial Dynamics(4180m)
Measurement <strong>of</strong> Vertical Heave0.25m x 0.25m grid with 5 cm grid cellsBamboo Skewers Inserted to 15cm Depth
Small Scale Sorted Circles - “Frost Boils” - Mount Barcr<strong>of</strong>t
Vertical Movement - Needle Ice
Vertical Movement - Primarily Seasonal Needle IceOctoberJuneJulyAugust
Results1991-1992 Vertical Heave MeasurementsMount Barcr<strong>of</strong>t Site27 frost boils sampled• 110 skewers placed (18 cm depth)76.3 %Completely heaved(> 18 cm)Average vertical heave16.8 cm/year
Average Annual Vertical Heave(cm)
Measurement <strong>of</strong> Horizontal Surface Movement0.5m x 0.5m grid with 10 cm grid cellsLincoln Memorial Pennies aligned with true north
Horizontal Movement
Dynamics<strong>of</strong>HorizontalMovementMarker Placement- Late Season- Avoids MarmotsMarkerMeasurement- Early Summer- After SnowmeltMarker Movement- Continues- Actively Sorting
Results <strong>of</strong>Lincoln Memorial GridPlacement (1992/93)5 grid <strong>sites</strong>; 362 total markers placed29% overturned40% rotated east or west,were buried, or wereturned on edge31% moved < margin <strong>of</strong> error± 2.0 cm lateral motion10° for rotation(Wilkerson, 1995)
Horizontal MovementSurface Markers: % Overturned
CONCLUSIONS1) Rates <strong>of</strong> Activity Vary- Water- Temperature (Freeze/Thaw)2) Elevational Gradient3) Highly Active Above 4150 m- Solifluction- Needle Ice4) Sporadic Activity at 3900 m- Frost Boils- Needle Ice5) Inactive (?) Below 3800 m
AcknowlegmentsWhite Mountain Research StationMinnesota State UniversityAssociation <strong>of</strong> Americ<strong>an</strong> GeographersAnne U. White Fund
Th<strong>an</strong>k You!Questions??
Same Site (4150 m) - Different Scales
Measurement <strong>of</strong> Sorted Polygons - Length <strong>an</strong>d WidthGr<strong>an</strong>odiorite(31 Polygons)S<strong>an</strong>dstone(31 Polygons)MaximumLengthWidth Border(Right Angle to Length)Width680 cm 367 cm 157 cm649 cm 361 cm 144 cmMount Barcr<strong>of</strong>t Gr<strong>an</strong>odioriteCampito Formation S<strong>an</strong>dstone
Difference in Me<strong>an</strong>s - Gr<strong>an</strong>odiorite vs S<strong>an</strong>dstoneMe<strong>an</strong> DifferenceSignific<strong>an</strong>ce LevelLength 18.72 cm 0.000Width 12.55 cm 0.000Depth 7.34 cm 0.000Mount Barcr<strong>of</strong>t Gr<strong>an</strong>odioriteCampito Formation S<strong>an</strong>dstone
CLAST SIZE ANALYSISLithology Length (X) Width (Y) Depth (Z)Gr<strong>an</strong>odiorite(N = 900)S<strong>an</strong>dstone(N = 900)24.27 cm 17.99 cm 10.34 cm8.51 cm 5.34 cm 2.99 cmMount Barcr<strong>of</strong>t Gr<strong>an</strong>odioriteCampito Formation S<strong>an</strong>dstone
Sorted Polygon Size <strong>an</strong>d Clast Size ResultsClast Size- Different - 0.000 Signific<strong>an</strong>cePattern Size- Similar - 0.95 Signific<strong>an</strong>ceCONCLUSION: Clast sizedifferences do not affect theprocesses that create thepatterns
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