MOUNT RAINIER
GEOLOGY & WEATHER
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Glacier Info - Winthrop Glacier

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NOTE: This page has been updated to show 2021 extents and changes

Winthrop Glacier
On the northern slope of Mount Rainier this glacier was named for Theodore Winthrop who traveled by the mountain in 1853 as the region's first "tourist." Winthrop popularized the northwest in his book The Canoe and The Saddle. He was born in Connecticut in 1828 and was killed in Virginia on June 10, 1861, early in the Civil War. (Reese, 2009)

STATISTICS AS OF 2021 (Beason et al., 2022):

Aerial Extent:
3.373 ± 0.178 square miles (8.735 ± 0.461 km2) (Rank: 2 of 29)

Debris Cover (Based on Beason, 2017 - not updated in 2021):
1.349 ± 0.077 square miles (3.494 ± 0.199 km2) (Rank: 1 of 29)

Estimated Glacial Volume: (See notes below)
0.0847 cubic miles (0.3530 km3)

Highest Elevation (Head):
14,379 feet (4,383 m)

Lowest Elevation (Terminus):
4,840 feet (1,475 m)

Elevation Range:
9,539 feet (2,907 m)

Length:
4.99 miles (8.03 km)

Average Slope:
29°

Average Flow Direction (Flows towards):
North northeast (13°)

CHANGE IN EXTENT, 1896-2015 (Beason, 2017):
Units 1896 1913 1971 1994 2009 2015 2021
Area, mi2 3.179 3.932 3.719 3.839 3.095 3.466 3.373
Area, km2 8.235 10.183 9.631 9.943 8.015 8.977 8.735

Area change between periods
1913 1971 1994 2009 2015 2021
1896 0.752 mi2
(1.949 km2)
0.539 mi2
(1.397 km2)
0.660 mi2
(1.709 km2)
-0.085 mi2
(-0.220 km2)
0.286 mi2
(0.742 km2)
0.193 mi2
(0.500 km2)
1913 -- -0.213 mi2
(-0.552 km2)
-0.093 mi2
(-0.240 km2)
-0.837 mi2
(-2.168 km2)
-0.466 mi2
(-1.207 km2)
-0.559 mi2
(-1.448 km2)
1971 -- 0.121 mi2
(0.312 km2)
-0.624 mi2
(-1.616 km2)
-0.253 mi2
(-0.655 km2)
-0.346 mi2
(-0.896 km2)
1994 -- -0.745 mi2
(-1.929 km2)
-0.373 mi2
(-0.967 km2)
-0.467 mi2
(-1.208 km2)
2009 -- 0.371 mi2
(0.962 km2)
0.278 mi2
(0.720 km2)
2015 -- -0.093 mi2
(-0.242 km2)

Percent change between periods
1913 1971 1994 2009 2015 2021
1896 23.66 % 16.96 % 20.75 % -2.67 % 9.01 % 6.08 %
1913 -- -5.42 % -2.35 % -21.29 % -11.85 % -14.22 %
1971 -- 3.24 % -16.78 % -6.80 % -9.31 %
1994 -- -19.40 % -9.72 % -12.15 %
2009 -- 12.00 % 8.98 %
2015 -- -2.69 %

ESTIMATED CHANGE IN VOLUME, 1896-2021 (Beason et al., 2022; George and Beason, 2017):
PLEASE see important notes about this, below...
Units 1896 1913 1971 1981* 1994 2009 2015 2021
Volume, mi3 0.0801 0.0990 0.0936 0.1257 0.0967 0.0779 0.0873 0.0847
Volume, km3 0.3337 0.4127 0.3903 0.5239 0.4030 0.3248 0.3638 0.3530
* = 1981 was the only year that glacial volumes have been measured. See note below.

Basal Shear Stress (τ): 3,212.05 lbs/ft2

Volume change between periods
1913 1971 1981 1994 2009 2015 2021
1896 0.0189 mi3
(0.0790 km3)
0.0136 mi3
(0.0566 km3)
0.0456 mi3
(0.1901 km3)
0.0166 mi3
(0.0693 km3)
-0.0021 mi3
(-0.0089 km3)
0.0072 mi3
(0.0301 km3)
0.0046 mi3
(0.0193 km3)
1913 -- -0.0054 mi3
(-0.0224 km3)
0.0267 mi3
(0.1111 km3)
-0.0023 mi3
(-0.0097 km3)
-0.0211 mi3
(-0.0879 km3)
-0.0117 mi3
(-0.0489 km3)
-0.0143 mi3
(-0.0597 km3)
1971 -- 0.0320 mi3
(0.1335 km3)
0.0030 mi3
(0.0127 km3)
-0.0157 mi3
(-0.0655 km3)
-0.0064 mi3
(-0.0265 km3)
-0.0090 mi3
(-0.0373 km3)
1981 -- -0.0290 mi3
(-0.1209 km3)
-0.0477 mi3
(-0.1990 km3)
-0.0384 mi3
(-0.1600 km3)
-0.0410 mi3
(-0.1709 km3)
1994 -- -0.0188 mi3
(-0.0782 km3)
-0.0094 mi3
(-0.0392 km3)
-0.0120 mi3
(-0.0500 km3)
2009 -- 0.0094 mi3
(0.0390 km3)
0.0068 mi3
(0.0282 km3)
2015 -- -0.0026 mi3
(-0.0108 km3)

Percent change between periods
1913 1971 1981 1994 2009 2015 2021
1896 23.66 % 16.96 % 56.97 % 20.75 % -2.67 % 9.01 % 5.77 %
1913 -- -5.42 % 26.93 % -2.35 % -21.29 % -11.85 % -14.47 %
1971 -- 34.20 % 3.24 % -16.78 % -6.80 % -9.57 %
1981 -- -23.07 % -37.99 % -30.55 % -32.62 %
1994 -- -19.40 % -9.72 % -12.41 %
2009 -- 12.00 % 8.67 %
2015 -- -2.97 %

With the exception of data in 1981, all values here are calculated estimates based on work by Driedger and Kennard (1986), which calculates glacier volumes with the following equations:

If Glacier Length (L) > 8,500 ft:


If Glacier Length (L) < 8,500 ft:


Basal shear stress (τ) is calculated as:


Where V is the calculated volume of the glacier (ft3), A is the calculated area of the glacier (ft2), ρ is the density of ice (1.779 slug/ft3), g is the acceleration of gravity (32.178 ft/s2), and α is the average slope of the glacier.

If you need a really good research project, recalculating the glacier volumes at Mount Rainier is the way to go!

NOTES:


Data References: Beason et al., 2022, Beason, 2017, George and Beason, 2017, Reese, 2009, and Driedger and Kennard, 1986