MOUNT RAINIER
GEOLOGY & WEATHER
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Glacier Info - South Tahoma Glacier

NOTE: The data shown here is based on the 2021 glacier update at Mount Rainier, and should be considered the most up-to-date data on glaciers at the park (2023-04-06).

South Tahoma Glacier
The South Tahoma Glacier is south of the Tahoma Glacier on the southwest side of Mount Rainier. The South Tahoma Glacier is separated from the Pyramid Glacier on the southeast by Success Cleaver and is drained by Tahoma Creek. (Reese, 2009)

Switch Glacier:

STATISTICS AS OF 2021 (Beason et al., 2023):
Aerial Extent:
0.752 ± 0.042 square miles (1.947 ± 0.109 km2) (Rank: 14 of 29)
Debris Cover - Based on data from 2015 (Beason, 2017):
0.215 ± 0.004 square miles (0.557 ± 0.010 km2) (Rank: 9 of 29)
Estimated Glacier Volume: (See notes below)
0.0169 ± 0.0059 cubic miles (0.0706 ± 0.0247 km3)
Highest Elevation (Head):
10,811 feet (3,295 m)
Lowest Elevation (Terminus):
6,625 feet (2,019 m)
Elevation Range:
4,186 feet (1,276 m)
Length:
2.00 miles (3.22 km)
Average Slope:
23.90°
Average Flow Direction (direction the glacier flows towards):
Southwest (219°)
Glacier Type:
C - Cirque Glacier, or Glacier Head Starts Below Summit

CHANGE IN EXTENT, 1896-2021 (Beason et al., 2023):
Units 1896 1913 1971 1994 2009 2015 2021
Area, mi2 2.288 1.323 1.128 0.862 0.852 0.773 0.752
Area, km2 5.926 3.427 2.922 2.233 2.206 2.002 1.947
Area Change Between Periods

1913 1971 1994 2009 2015 2021
1896-0.965 mi2
(-2.499 km2)
-1.160 mi2
(-3.005 km2)
-1.426 mi2
(-3.694 km2)
-1.436 mi2
(-3.720 km2)
-1.515 mi2
(-3.924 km2)
-1.536 mi2
(-3.979 km2)
1913---0.195 mi2
(-0.506 km2)
-0.461 mi2
(-1.195 km2)
-0.472 mi2
(-1.221 km2)
-0.550 mi2
(-1.425 km2)
-0.572 mi2
(-1.480 km2)
1971---0.266 mi2
(-0.689 km2)
-0.276 mi2
(-0.716 km2)
-0.355 mi2
(-0.920 km2)
-0.376 mi2
(-0.975 km2)
1994---0.010 mi2
(-0.027 km2)
-0.089 mi2
(-0.231 km2)
-0.110 mi2
(-0.286 km2)
2009---0.079 mi2
(-0.204 km2)
-0.100 mi2
(-0.259 km2)
2015---0.021 mi2
(-0.055 km2)
Percent Change Between Periods

1913 1971 1994 2009 2015 2021
1896-42.17%-50.70%-62.33%-62.78%-66.22%-67.15%
1913---14.75%-34.86%-35.63%-41.59%-43.19%
1971---23.59%-24.49%-31.48%-33.36%
1994---1.19%-10.34%-12.79%
2009---9.26%-11.74%
2015---2.74%

ESTIMATED CHANGE IN VOLUME, 1896-2021 (Beason et al., 2023):
PLEASE see important notes about this, below...
Glacier-specific Scaling Parameter, c:
0.031247
Units 1896 1913 1971 1994 2009 2015 2021
Volume, mi3 0.0777 0.0367 0.0295 0.0204 0.0201 0.0176 0.0169
Volume, km3 0.3238 0.1531 0.1230 0.0852 0.0838 0.0733 0.0706
Volume Change Between Periods

1913 1971 1994 2009 2015 2021
1896-0.041 mi3
(-0.171 km3)
-0.048 mi3
(-0.201 km3)
-0.057 mi3
(-0.239 km3)
-0.058 mi3
(-0.240 km3)
-0.060 mi3
(-0.250 km3)
-0.061 mi3
(-0.253 km3)
1913---0.007 mi3
(-0.030 km3)
-0.016 mi3
(-0.068 km3)
-0.017 mi3
(-0.069 km3)
-0.019 mi3
(-0.080 km3)
-0.020 mi3
(-0.082 km3)
1971---0.009 mi3
(-0.038 km3)
-0.009 mi3
(-0.039 km3)
-0.012 mi3
(-0.050 km3)
-0.013 mi3
(-0.052 km3)
1994--0.000 mi3
(-0.001 km3)
-0.003 mi3
(-0.012 km3)
-0.003 mi3
(-0.015 km3)
2009---0.003 mi3
(-0.010 km3)
-0.003 mi3
(-0.013 km3)
2015---0.001 mi3
(-0.003 km3)
Percent Change Between Periods

1913 1971 1994 2009 2015 2021
1896-52.73%-62.01%-73.70%-74.13%-77.35%-78.20%
1913---19.62%-44.37%-45.27%-52.09%-53.87%
1971---30.79%-31.92%-40.39%-42.61%
1994---1.63%-13.87%-17.08%
2009---12.45%-15.71%
2015---3.73%
Important comments about the calculation of volume shown here

The calculation of glacial volume shown on this page is based on an analysis of two methods used at Mount Rainier in the past (Driedger and Kennard [1986]; and Nylen [2001]) as well as the most recent literature review for glacier area-volume scaling (Please review Beason et al. [2023] for an in-depth discussion about this issue). It should be noted that simply converting area to volume with an equation is extremely difficult and the values presented here have extremely large error margins (likely ± 35% or more). With that in mind, the values presented here should give you an estimate of the glacial volume and change in volume over time. Please use these data very carefully with those caveats.

The calcuation of the volume is as follows:

\[V_i = {(c_iA_i^{1.375}) + (c_nA_i^{1.36}) \over 2}\]

Where:
\(V_i\) = Average volume for the glacier in question (km3);
\(c_i\) = The glacier-specific scaling parameter (back-calculated from glacier area and volume in 1971 in Driedger and Kennard (1986); Method described in Beason et al. (2023). The value for the South Tahoma Glacier is 0.031247 (this is also listed above the volume graph);
\(c_n\) = The back-calculated scaling parameter from Nylen (2001) of 0.0255; and
\(A_i\) = The measured volume of the glacier in question (km2).

This is essentially an average of the back-calculated Dreidger and Kennard (1986) and Nylen (2001) methods (D&K is in the first parenthesis; Nylen in the second). For example, for the South Tahoma Glacier in 2021, you can find the following individual volumes:
Back-calculated Dreidger and Kennard (1986) Method: 0.0187 mi3 (0.0781 km3).
Back-calculated Nylen (2001) Method: 0.0151 mi3 (0.0631 km3).
Average of the two (above equation and values listed for 2021 here): 0.0169 mi3 (0.0706 km3).
Official volume estimate listed above, with error: 0.0169 ± 0.0059 mi3 (0.0706 ± 0.0247 km3).

As you can see, the D&K method tends to produce higher values and Nylen produces lower values; the average of these two methods probably estimates the glacial volume. Until further research is done in this area and we can develop a better method or equation to determine volumes, this is the method we are using to determine glacial volumes. For more information about this method, please read the methods section of Beason et al. (2023).

NOTES:

-- No Notes supplied --

RAW DATA: