Geographic, hydrological, and climatic significance of rock glaciers in the Great Basin, USA

Figures & data

Figure 1. Map of the hydrographic Great Basin study region, United States, showing mountain ranges containing rock glaciers, ranges with persistent ice fields (marked with *), and eight subregions used in analysis. Mountain ranges are defined in Table 1. Subregions: SN = Sierra Nevada (not enclosed by polygon); SW = southwest; NW = northwest; SC-W = south-central west; SC-E = south-central east; NC = north central; NE = northeast; SE = southeast.

Figure 2. Examples of rock-glacier morphology types mapped in the Great Basin. (a) Cirque rock glacier (RGC); (b) crest-headwall rock glacier (TALC); (c) valley wall rock glacier (TALV; protalus rampart).

Figure 3. Examples of condition types estimated for features mapped in the Great Basin. (a) Active (A1), Mt. Gibbs, Sierra Nevada, California; (b) active front (A1), Mammoth Crest, Sierra Nevada, California; (c) likely active (A2), Moores Canyon, Toquima Range, Nevada; (d) relict (R), Cougar Peak, Jarbidge Range, Nevada.

Table 1. Geographic attributes for rock glaciers of the Great Basin. Intact rock glaciers include condition classes A1 and A2; relict rock glaciers are class R.

				Area (km^2 × 10^2)								Rock-Glacier Attributes
				Intact		Relict		Percent of Range		Aspect (% N-NE)			Snout Angle (°)		% Furrowed		% Forefields (all features)
Mountain Range	Map Code	N	Elevation mean (m)	Total	Mean	Total	Mean	(%)^a	Range Area^b (km^2)	Active	Relict	% Active	Active	Relict	Active	Relict	WM, SP, LK	RK	% Active with Ice Fields
Bear River Mountains	BR	2	2,678	0.9	0.9	3.2	3.2				0	50	48	7	0	0	100	0	0
Carson Range	CR	10	2,830			14.2	1.4	0.05	304		50	0		22		0	60	0	0
Copper Mountains	CP	1	2,780			1.6	1.6				100	0		37		0	0	0	0
Deep Creek Mountains	DC	7	3,137			14.5	2.1	0.14	103		57	0		28		29	14	14	0
East Humboldt Range	EH	11	2,881	18.8	6.3	9.2	1.2	0.26	107	67	63	27	24	26	33	13	82	18	67
Fish Lake Mountains	FL	32	3,163	76.4	25.5	223.6	7.7	1.34	225	67	34	9	24	24	67	55	53	0	0
Independence Mtns	IM	1	2,657			6.0	6.0				0	0		28		0	0	100	0
Jarbidge Range	JR	22	2,900	88.9	5.9	38.0	5.4	0.49	260	73	43	68	23	15	27	0	45	14	60
Markagunt Plateau	MP	3	3,173			9.4	3.1	0.06	158		0	0		20		0	100	0	0
Marys River Mountains	MA	1	2,924			0.4	0.4				100	0		9		0	0	100	0
Monitor Range	MR	3	3,164			2.5	0.8	0.06	45		67	0		24		0	33	0	0
Pine Forest Range	PF	2	2,516			3.1	1.6				50	0		22		0	100	0	0
Raft River Mountains	RR	2	2,796			4.3	4.3				100	0		31		0	50	0	0
Ruby Mountains North^c	RN	26	3,022	10.3	1.7	42.5	2.5	0.25	227	83	58	33	32	25	33	8	72	17	0
Ruby Mountains South^d	RS	2	2,970			4.2	1.7				20	0		27		0	60	20	0
Schell Creek Range	SC	19	3,063			126.1	6.6	0.40	319		58	0		23		11	42	0	0
Sierra Nevada North^e	Sie^l	9	2,508			18.3	2.0	0.24	76		44	0		24		11	0	22	0
Sierra Nevada Central^f	Sie^l	282	3,240	2029.2	11.2	745.4	7.3			68	55	64	29	24	43	19	49	32	24
Sierra Nevada South^g	Sie^l	181	3,470	1980.2	20.8	785.1	9.1	2.1 ^m	2642 ^m	65	49	52	32	27	63	22	61	27	33
Silver Peak Range	SP	3	2,737			34.1	11.4	0.10	337		0	0		32		67	0	0	0
Snake Mountains	SK	1	2,366			28.2	28.2				0	0		23		0	0	0	0
Snake Range North^h	SN	3	3,077			8.8	2.9	0.15	59		0	0		20		33	0	0	0
Snake Range South^i	SS	22	3,236	45.4	7.6	88.6	5.5	0.43	311	83	56	27	26	23	50	19	45	14	33
Steens Mountains	SM	9	2,633	11.3	11.3	8.6	1.1	0.30	67	100	50	11	36	25	100	0	56	11	100
Strawberry Mountains	SB	2	2,265			4.2	2.1				100	0		22		0	50	0	0
Sweetwater Mountains	SW	9	3,059	57.0	11.4	22.8	5.7	0.50	160	40	25	56	22	25	60	25	67	0	0
Toiyabe Range North^j	TN	1	2,861			7.0	7.0				100	0		18		0	0	0	0
Toiyabe Range Main^k	TY	25	3,079	49.1	12.3	34.3	1.6	0.25	330	25	57	16	29	25	100	5	20	36	0
Toquima Range	TQ	17	3,194	14.4	3.6	25.5	2.0	0.81	49	50	62	24	29	23	50	0	29	41	0
Tushar Mountains	TM	12	3,278	22.9	7.6	65.1	7.2	0.70	125	67	78	25	28	29	100	22	25	0	33
Uinta Mountains	UM	35	3,154	68.6	9.8	196.0	7.0	0.30	890	71	32	20	29	23	57	0	60	0	0
Warner Mountains	WM	13	2,617	5.4	1.8	9.4	0.9	0.06	232	67	40	23	27	20	33	0	46	15	0
Wasatch Mountains	WA	50	3,005	561.4	21.6	303.1	12.6	1.79	483	54	50	52	27	22	73	17	38	14	27
Wassuk Range	WS	2	2,935			6.0	3.0				100	0		26		0	0	0	0
White Mountains	WT	21	3,449	103.0	9.3	271.5	33.9	0.70	531	77	50	62	26	17	62	13	43	52	8
Yamsay Mountain	YA	1	2,376			0.1	0.1				100	0		12		0	100	0	0
Overall			3,196	5143	13.7	3165	6.8	1.09	8070	66	50	45	29	24	52	17	50	23	22

^a All categories of rock glaciers (A1, A2, R) are included; percents are calculated for ranges with more than two features.

^b Range area based on area above contour of the minimum elevation of rock glaciers (all categories) within the range.

^c North of Harrison Pass; 40.325,279°, −115.511,215°.

^d South of Harrison Pass; 40.325,279°, −115.511,215°.

^e North of Carson Pass; 38.787,277°, −119.944,435°.

^f South of Carson Pass; 38.787,277°, −119.944,435° and north of Horton Canyon (Mt. Tom); 37.320,215° −118.678,593°.

^g South of Mt. Tom; 37.320,215°, −118.678,593°.

^h North of Sacramento Pass; 39.142,659°, −114.336,273°.

ⁱ South of Sacramento Pass; 39.142,659°, −114.336,273°.

^j North of Austin Summit; 39.481,735°, −117.037089°.

^k South of Austin Summit; 39.481,735°, −117.037089°.

^l “Sierra Nevada” on map.

^m Value is for the Sierra Nevada Central and South combined.

WM = wet meadow; RK = rock; SP = spring; LK = lake.

Table 2. Geographic attributes for persistent ice fields of the Great Basin.

			Area (km^2 x 10^2)
Mountain Range	N	Elevation mean (m)	Total	Mean	Aspect (% N-NE)	% Bergschrund^a
East Humboldt Range	9	3,088	1.8	0.2	67	0
Jarbidge Range	10	3,024	2.6	0.3	100	0
Ruby Mountains North	15	3,082	2.3	0.2	93	0
Schell Creek Range	1	3,459	0.1	0.1	100	0
Sierra Nevada Central^b	100	3,485	197.0	2.0	98	25
Sierra Nevada South^c	81	3,737	328.3	4.1	98	22
Snake Range South	2	3,415	0.9	0.5	100	0
Steens Mountains	1	2,825	0.3	0.3	100	0
Sweetwater Mountains	2	3,336	0.5	0.3	100	0
Tushar Mountains	1	3,561	0.1	0.1	100	0
Uinta Mountains	3	3,556	1.5	0.5	100	0
Warner Mountains	2	2,552	1.0	0.5	50	0
Wasatch Mountains	8	3,190	6.3	0.8	100	0
White Mountains	2	4,031	0.2	0.1	100	0
Overall	237	3,494	543.0	2.3	96	16

^a Includes major fractures parallel to slope contour and near top of the ice field.

^b South of Carson Pass; 38.787277°, −119.944435° and north of Horton Canyon (Mt. Tom); 37.320215° −118.678593°.

^c South of Mt. Tom; 37.320215°, −118.678593°.

Figure 4. Discriminant analysis of subregions in the hydrographic Great Basin (Figure 1 for subregion names) and twenty-five PRISM climate variables (Table 3 for variables). Dots are PRISM climate tiles containing rock-glacier sites; overlapping sites are contained in many of the single dots: NE = purple; SE = green; SC-E = brown; SC-W = gold; NC = light green; NW = blue; SW = pink; SN = yellow-green. Larger ellipsoids indicate 50 percent concentration of the points; smaller (inner) ellipsoids indicate 95 percent confidence intervals of the class means. The mean misclassification rate was 1.4 percent.

Figure 5. Discriminant analysis of rock-glacier  condition classes in the hydrographic Great Basin and twenty-five PRISM climate variables (see Table 3). Dots are PRISM climate tiles containing rock-glacier sites; overlapping sites are contained in many of the single dots. Class A1 (active) = brown; class A2 (inactive) = purple; class R (relict) = green. Larger ellipsoids indicate 50 percent concentration of the points; smaller (inner) ellipsoids indicate 95 percent confidence intervals of the class means. The mean misclassification rate was 39 percent.

Table 3. Summary of mean climatic data by subregions, rock-glacier condition class, and overall for the Great Basin (GB). Data extracted from PRISM climate model (1981–2010 normals, Daly, Neilson, and Phillips 1994). Subregions: NC = north-central; NE = northeast; NW = northwest; SC-E = south-central east; SC-W = west-central west; SE = southeast; SN = Sierra Nevada; SW = southwest. Classes: A1 = active; A2 = inactive; R = relict.

		Subregions
	Overall GB	NC	NE	NW	SC-E	SC-W	SE	SN	SW	Class A1	Class A2	Class R
Number of sites	842	65	88	27	51	46	47	483	35	219	156	467
Annual precipitation (mm)	1010	956	1254	1026	712	661	941	1074	583	1131	1029	946
December precipitation (mm)	144	116	139	154	60	55	92	175	82	180	148	126
January precipitation (mm)	158	110	147	139	72	65	85	198	95	204	165	135
Feb precipitation (mm)	144	95	130	128	75	62	95	178	86	180	147	126
July precipitation (mm)	24	23	41	14	32	37	48	17	23	20	24	25
August precipitation (mm)	25	24	49	17	36	36	64	15	22	18	24	28
September precipitation (mm)	35	38	77	25	39	31	56	26	21	32	36	36
Annual Temp	1.7	2.2	2.0	3.3	2.1	2.7	1.5	1.3	1.8	0.6	1.6	2.2
Annual Tmax (°C)	7.3	7.4	7.5	8.6	7.6	8.6	7.0	7.0	7.7	6.1	7.2	7.9
December Tmax (°C)	−0.7	−2.2	−2.4	−0.3	−2.4	0.5	−1.2	−0.1	−0.2	−1.2	−0.7	−0.5
January Tmax(°C)	−0.5	−1.9	−2.1	−2.7	−2.3	0.6	−1.3	0.1	0.2	−1.0	−0.5	−0.3
February Tmax (°C)	−0.2	−0.9	−0.9	0.7	−1.2	0.7	−0.3	0.0	−0.1	−1.1	−0.3	0.2
July Tmax (°C)	−0.2	−0.9	−0.9	0.7	−1.2	0.7	−0.3	0.0	−0.1	−1.1	−0.3	0.2
August Tmax (°C)	17.6	19.7	19.0	20.4	19.5	20.3	18.8	16.2	18.5	15.6	17.5	18.6
September Tmax (°C)	13.7	14.8	14.1	16.1	14.7	14.5	14.5	13.1	13.7	12.2	13.5	14.5
Annual Tmin (°C)	−4.0	−3.1	−3.4	−2.0	−3.4	−3.2	−3.9	−4.5	−4.1	−4.9	−4.1	−3.5
December Tmin (°C)	−10.7	−11.1	−12.1	−8.7	−11.4	−10.4	−11.9	−10.4	−9.9	−11.0	−10.7	−10.5
January Tmin (°C)	−10.9	−11.0	−12.1	−8.9	−11.6	−10.5	−11.9	−10.7	−10.1	−11.4	−10.9	−10.6
February Tmin (°C)	−11.5	−11.3	−12.2	−9.1	−11.6	−11.2	−11.8	−11.6	−10.9	−12.2	−11.5	−11.1
July Tmin (°C)	5.3	6.2	7.2	6.1	6.6	5.1	6.9	4.5	5.6	4.2	5.2	5.8
August Tmin (°C)	6.9	5.9	6.5	5.9	6.1	4.6	6.0	4.1	5.0	3.8	4.8	5.4
September Tmin (°C)	1.3	1.9	2.3	2.6	1.9	1.2	2.2	0.9	1.7	0.4	1.3	1.8
July dewpoint T (°C)	−1.9	−3.7	1.2	−2.7	−5.3	−4.6	−0.8	−1.7	−1.4	−2.1	−1.6	−1.9
VPDmax (mbar)	16.6	19.0	16.6	19.3	20.6	21.2	17.9	15.0	17.8	14.2	16.1	17.8
VPDmin (mbar)	4.5	5.9	4.7	5.3	6.6	5.1	5.3	3.8	4.7	3.9	4.3	4.8

Table 4. Water volume estimated for rock glaciers and persistent ice fields of the Great Basin. For rock glaciers, volume was calculated only for features assessed as intact (condition classes A1 or A2). Blank cells indicate mountain ranges without active rock glaciers or without ice fields.

	Total Water Volume (km^3 × 10^4)
Mountain Range	RKG^a	ICF^b	Ratio of Rock Glacier to Ice Field Water Volume
Bear River Mountains	0.79
East Humboldt Range	24.84	0.54	46:1
Fish Lake Mountains	147.18
Jarbidge Range	118.20	0.89	133:1
Ruby Mountains North	10.38	0.71
Schell Creek Range		0.02
Sierra Nevada Central	3,305.06	177.11	19:1
Sierra Nevada South	3,657.36	469.57	8:1
Snake Range	68.19	0.39	175:1
Steens Mountains	16.44	0.10	164:1
Sweetwater Mountains	87.22	0.16	545:1
Toiyabe Range Main	76.69
Toquima Range	17.42
Tushar Mountains	31.38	0.01	3138:1
Uinta Mountains	104.78	0.68	1625:1
Warner Mountains	6.01	0.39	15:1
Wasatch Mountains	1,088.85	3.26	334:1
White Mountains	163.30	0.04	4,082:1
Total (9,577.5 km^3 × 10^4)	8,924.11	653.39	14:1
Percent of Total	93	7

^aRKG = rock glacier.

^bICF = ice field.

Daly, C. R., R. P. Neilson, and D. L. Phillips. 1994. A statistical-topographic model for mapping climatological precipitation over mountainous terrain. Journal of Applied Meteorology 33:140–58. doi:10.1175/1520-0450(1994)033<0140:ASTMFM>2.0.CO;2.

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