Question: The longest and largest glacier in France is smaller than what glacier in the Alps?
Context: Harrison Glacier is located in the US state of Montana in Glacier National Park.  Situated on a southeast facing ridge immediately south of Mount Jackson, Harrison Glacier is the largest glacier in Glacier National Park and was estimated in 2005 to have an area of 466 acre .  Though many experts have stated that all the glaciers in Glacier National Park may disappear by the year 2030, Harrison Glacier lost only 9 percent of its surface area in the 40-year period between 1966 and 2005 and will likely still exist well beyond 2030.  Compared to many of the vanishing glaciers in Glacier National Park, Harrison Glacier has a much higher altitude accumulation zone (approximately 9000 ft ) which has allowed it to maintain some equilibrium in its glacier mass balance.  Comparing images of the glacier taken in 1913 with those from 2009, indicates that the glacier has experienced thinning and retreat. The Aletsch Glacier (German: "Aletschgletscher" ) or Great Aletsch Glacier ("Grosser Aletschgletscher ") is the largest glacier in the Alps.  It has a length of about 23 km (2014), has about a volume of 15.4 km3 (2011), and covers about 81.7 km2 (2011) in the eastern Bernese Alps in the Swiss canton of Valais.  The Aletsch Glacier is composed of four smaller glaciers converging at Concordia Place, where its thickness was measured by the ETH to be still near 1 km .  It then continues towards the Rhône valley before giving birth to the Massa.  The Aletsch Glacier is – like most glaciers on this world – a retreating glacier.  As of 2016, since 1980 it lost 1.3 km of its length, since 1870 3.2 km , and lost also more than 300 m of its thickness. The Mer de Glace is a valley glacier located on the northern slopes of the Mont Blanc massif, in the French Alps.  It is 7.5 km long and 200 m deep but, when all its tributary glaciers are taken into account, it can be regarded as the longest and largest glacier in France, and the second longest in the Alps after the Aletsch Glacier. Arapaho Glacier was an alpine glacier in a cirque immediately southeast of North Arapaho Peak, in Roosevelt National Forest in the U.S. state of Colorado.  The glacier was just east of the Continental Divide.  Arapaho Glacier was the largest glacier in the state of Colorado and helped provide water for the city of Boulder, Colorado.  The glacier has a negative glacier mass balance and lost over 52% of its surface area during the 20th Century. Bara Shigri is the largest glacier located in the state of Himachal Pradesh, India, Bara-Sigri glacier which is the second longest glacier in Himalaya after Gangotri, both are around 30 km long.  The glacier is located in the Chandra Valley of Lahaul.  The glacier feeds the Chenab River. Boston Glacier is located in a large cirque below several mountain peaks in North Cascades National Park in the U.S. state of Washington.  The glacier is approximately 1 mi long but nearly 3.5 mi wide and is the largest glacier in North Cascades National Park.  Extending in an arc from the north of Forbidden Peak, the glacier is also flanked by Boston Peak to the southwest and Buckner Mountain at its eastern margin.  Between Boston Peak and Buckner Mountain, the glacier lies below the arête known as Ripsaw Ridge.  Another arete extending between Boston Mountain and Forbidden Peak and further north separate Boston Glacier from the nearly adjoining Quien Sabe and Forbidden Glaciers. Boston Glacier has been in an overall state of retreat since the end of the Little Ice Age around the year 1850.  A moderate advance occurred between 1950 and the mid-1970s however the retreat resumed and between the years 1972 and 2006 the glacier terminus retreated 1470 ft . Mammoth Glacier is in the Bridger Wilderness of Bridger-Teton National Forest, in the U.S. state of Wyoming.  The glacier is on the west side of the Continental Divide which separates it from Dinwoody Glacier to the east.  Mammoth Glacier is the largest glacier on the west side of the Continental Divide of the Wind River Range and occupies a large, north facing cirque on the north slopes of Twin Peaks and just west of Mount Woodrow Wilson.  Mammoth Glacier is part of the largest grouping of glaciers in the American Rocky Mountains. The Harvard Glacier is a large tidewater glacier in the Alaska's Prince William Sound.  The glacier has a 1.5-mile (2 km) wide face where it calves into the College Fjord.  It is 300 ft thick and covers 120,000 acres of Chugach National Forest.  The Harvard Glacier is the second largest glacier in the Prince William Sound, after the Columbia Glacier.  It is a popular destination of cruise ships in the Prince William Sound. The Theodul Glacier (also spelled "Theodule Glacier"; German: "Theodulgletscher" ) is a glacier of the Alps, located south of Zermatt in the canton of Valais.  It lies on the Swiss side of the Pennine Alps, although its upper basin touches the Italian region of the Aosta Valley.  The glacier descends from the west side of the Breithorn (4164 m ) and splits into two diverging branches above Gandegg: the Upper Theodul Glacier ("Oberer Theodulgletscher"), spilling on a high plateau near Trockener Steg, together with the Furgg Glacier, and the Lower Theodul Glacier ("Unterer Theodulgletscher"), reaching a height of about 2500 m above the Gorner Glacier.  Both branches are part of the Rhone basin, through the rivers Gornera, Mattervispa, and Vispa.  Slightly above the glacier splitting is the Theodul Pass, crossing the border between Switzerland and Italy, and connecting Zermatt to Breuil-Cervinia.  On the west, the Theodul Glacier is overlooked by the Matterhorn. Bering Glacier is a glacier in the U.S. state of Alaska.  It currently terminates in Vitus Lake south of Alaska’s Wrangell-St.  Elias National Park, about 10 km from the Gulf of Alaska.  Combined with the Bagley Icefield, where the snow that feeds the glacier accumulates, the Bering is the largest glacier in North America.  Warmer temperatures and changes in precipitation over the past century have thinned the Bering Glacier by several hundred meters.  Since 1900 the terminus has retreated as much as 12 km .  The Bering Glacier exhibits "surges", acceleration events of the flow rate of the glacier, every 20 years or so.  During these periods the glacier terminus advances.  The surges are generally followed by periods of retreat, so despite the periodic advances the glacier has been shrinking overall.  Most glaciers along the Alaskan coast have been retreating along with the Bering Glacier.
Answer: Aletsch Glacier