Rock Glaciers and Related Landforms in the Sierra Nevada ...

2. Valley Wall Rock Glaciers (RGV)Francis Cr CynMean Elev: 3243mShape: 12% L61% W27% EMean size: 3 haSlope AspectE Fk Rock Creek

3. Boulder Streams (BSC)Helen LkMean Elev: 3317mShape: 39% L7% W54% EMean size: 5 haSlope AspectKuna Crest

5. Patterned Ground RIFsNets & StripesToquima Range, NVMean Elev: 3273mShape: 33% L20% W47% EMean size: 1.1 haSlope AspectSorted CirclesSilver Pine Lk, Mt Dunderberg

Relict (LIA/Pleistocene) RIFs are also common;Warren CrestThese appear to lackpersistent ice25% of mapped featuresDana Cliffs

RIF Climate Modeling:1. Imported RIF locations into GIS2. Intersected with 30 arcsec 1970-2000 PRISM data (Daly et al. 1994)3. Downscaled to RIF locations using regression approach (Hamman & Wang 2005)

Canonical Plot for the First TwoVectors from Discriminant Analysis6 RIF Classes and 10 PRISM ClimateVariablesLetters indicate mean of thedistribution for each classClasses:A = Scree Boulder StreamsB = Flowing Boulder StreamsC = Solifluction FieldsD = Cirque Rock GlaciersE = Valley Rock GlaciersF = Patterned Ground

Comparisons of Pleistocene (P)vs Holocene (H) TemperaturesEleven Watersheds with Paired Pleistocene and Holocene RIFs (N = 53)Two Approaches:- Elevation Difference x Std Lapse Rate (-6.5C/km)- Direct PRISM Estimates by ElevationPleistocene – Dana CliffsHolocene – Kuna Crest

GLACIERS IN A WARMING WORLDIce glaciers worldwide have been melting during the past 120 yearsDecreases in AreaDana Glacier, >65%,Basagic 2008Russell 1883 2008Decreases in MassS Fk Glacier, WA;-25%Fountain 2004

Rock glaciers & RIFs, however, resist meltingand lag in response to warming…Rock debris insulatesembedded ice againstsolar radiation

Pleistocene Rock Glaciers Overrode Tioga MorainesLag in Ablation during Warming ClimatesLee Vining CynRGRGTioga lateral moraine

RIFs are sources of persistent waterStreams run through the dry season* Embedded ice is source of water* Rock mantle reduces evaporation* Unique air circulation supercools rock matrixWe install data-loggers inoutlet streams & underadjacent rocks (air)Kuna Lk, Kuna Crest

RIF outlet streams freeze but don’t dryiButton RecordsOutlet streams freeze°CSnow coversSnow melts

RIF streams & springs were still runningas of late Sept 2007 (extreme dry year)Dana Fk, TuolumneBSCWhereas many non-RIF streams & springsdried up

Water chemistry of RIF outlet streamsdiffers from other Sierran watersDave Clow (USGS)

Rock glaciers discharge water differentthan ice glaciersWater seeps rather than rushes downcanyon& persists through autumn,even in dry yearsWarren ForkLundy Cyn

RIF canyons often lack central, incisedstreams typical of ice-glacial canyonsPleistocene RGC, Mt DunderbergParker CynPleistocene RGC, Gibbs CynLee Vining Cyn

RIFs provide unique wetland alpine habitats…increasingly rare & important as climates warmParker RGC; Pleistocene relictGibbs BSC; Holocene active

RIF Wetland Areas (means)Age Class n RG WetlandArea (ha) Area (ha)------------ ----- -- -------- ---------Pleistocene RGC 12 100 252Modern RGC 11 10 20RGV 8 2 5BSC 9 16 10Wetland onDunderberg RGCDunderberg Pleistocene RGC,below RG snout

Plant Species DiversityRIF Wetland Willow & Sedge CommunitiesRock glacier wetlands harbor rare species in otherwisexeric alpine locations; these wetlands will persist underwarming climates and serve as important plant refugia

Plant Species Diversity - Rock Glacier SurfacesBarney Rock Glacier Study - Duck Pass, Mammoth CrestpatchWe assessed plant species diversity &cover on all (60) plant patches

Biogeographic Affinities of Plants on BRG PatchesSoil patches on rock glacier surfaces provide cooler than expected habitats; theseextend the range of higher elevation taxa downward. Patches also provide“rescue” habitat for lower elevation species stressed by warming climates.1. Higher Elevation Taxa: 14 spp (47%)E.g., Erigeron pygmaeus, Eriogonum incanum,Primula suffrutescens2. Lower Elevation, Cool/Mesic Taxa: 3 spp (10%)E.g., Cirsium scariosum,Pellea breweri3. Cosmopolitan Mountain Taxa : 18 spp (60%)E.g., Leptodactylon pungens, Ericameria suffruticosa60 Plant Patches7.9% of BRG1.3% Plant Cover

RIFs provide unique animal habitats1. Beavers* Beavers are exotic in the Eastern Sierra -widely introduced but minimally established;* Beavers established in canyons where conditionssupport dam-building = low volume streams, widely distributed springs;* Beavers established in RG Cyns; Beavers further enhance water retention.Dunderberg Pleistocene RGCLundy Pleistocene RGC

2. American PikaUse rock-glacier surfaces abundantlyAbundant around plant patches - Barney RGPhoto: J BishopAbundant near RG snouts

Pika appear to benefit from RIF internal coldair-circulation,cool micro-climates,Photo: J. Page…and associatedwetland vegetationGibbs Cyn

Summary• Rock glaciers & related Rock-Ice Features are widely distributedin high Sierran canyons, especially east of the crest• RIFs store and discharge water persistently and lag inresponse to warming• RIFs distribute waterbroadly across thelandscapeMt Snowden Rock Glacier

Summary, cont’d• RIFs support persistent wetland habitats otherwise rare inSierran alpine regions & high plant species diversitiesSherwin Crest RGs• RIFs provide cold microclimatesand habitat for wide range ofplant species on soil “islands”• RIFs support important habitatfor wetland and cool-dependentanimals, including abundantrefugial habitat for pikaPhoto: A. Shcherbinaphew