Question: Which glacier is named after an early American conservationist and explorer: Gem Glacier or Grinnell Glacier?
Context: Grinnell Glacier is in the heart of Glacier National Park in the U.S. state of Montana.  The glacier is named for George Bird Grinnell, an early American conservationist and explorer, who was also a strong advocate of ensuring the creation of Glacier National Park.  The glacier is in the Lewis Range and rests on the north flank of Mount Gould at an altitude averaging 7000 ft , in the Many Glacier region of the park. Lake Josephine is located in Glacier National Park, in the U. S. state of Montana.  Swiftcurrent Lake is immediately to the northeast of Lake Josephine and the two lakes are separated by a short (.3 mi ) stream.  Lake Josephine is accessible via the Grinnell Glacier Trail which follows the west shoreline of the lake for 1 mi . Many Glacier is an area within Glacier National Park which is located in the U.S. state of Montana.  The Many Glacier region is located north of the Going-to-the-Sun Road, on the east side of the park.  Lake Sherburne is the large lake in the area and the Many Glacier Hotel, the largest hotel within the park, is along the shore of the adjacent Swiftcurrent Lake.  The Many Glacier Hotel and surrounding buildings are a National Historic Landmark, with original construction dating back to 1915.  Many Glacier is surrounded by the high peaks of the Lewis Range, and numerous hiking trails can be accessed from the area.  The region is noted for numerous lakes, waterfalls and dense coniferous forests interspersed with alpine meadows. Major sites in the immediate vicinity that can be accessed by trails include Lake Josephine, Grinnell Lake, Grinnell Glacier, Cracker Lake, Granite Park Chalet, Iceberg Cirque and the Ptarmigan Tunnel, which is a hiking tunnel carved through the mountainside during the 1930s.  Tour boats allow visitors an opportunity to venture onto Swiftcurrent Lake.  Other activities in the region include ranger guided nature hikes, horseback riding, fishing and camping. Grinnell Lake is located in Glacier National Park, in the U. S. state of Montana.  Named after George Bird Grinnell, the lake has an opaque turquoise appearance from the rock flour (silt) which is transported to the lake from Grinnell Glacier.  Grinnell Lake is accessible via the Grinnell Glacier Trail and is 3.2 mi from the Many Glacier Hotel. Upper Grinnell Lake is located in Glacier National Park, in the U. S. state of Montana.  Upper Grinnell Lake is a proglacial lake which formed in the 1930s as Grinnell Glacier retreated.  The lake is often filled with small icebergs which have been breaking off Grinnell Glacier.  Upper Grinnell Lake can be reached by trail and is a 5.5 mi hike from the Many Glacier Hotel. Gem Glacier is the smallest named glacier in Glacier National Park (U.S.).  Located on the east (Glacier County) side of the Continental Divide arête known as the Garden Wall, the glacier is situated on the cliff face above the better known Grinnell Glacier.  Gem Glacier is a hanging glacier, and drapes down from the north face of the steep arete to which it is attached.  Gem Glacier is only 5 acre in area and is far below the 25 acre threshold often cited as qualifying as an active glacier.  Between 1966 and 2005, Gem Glacier lost 30 percent of its acreage and Grinnell Glacier lost 40 percent. The Highline Trail in Glacier National Park is a scenic hiking trail stretching 7.6 mi from Logan Pass to Granite Park Chalet, and continuing another 11.9 mi from there to Fifty Mountain Campground.  The trail follows the Garden Wall ridge and the continental divide for most of its length.  The trail offers scenic views of glaciated U-shaped valleys.  A 1.2 mi round trip side trail takes hikers up the side of the Garden Wall to an overlook to Grinnell Glacier. The Salamander Glacier is in Glacier National Park in the U.S. state of Montana.  The glacier lies on a shelf on the east side of the arête which is part of the Continental Divide, at an average elevation of 7200 ft above sea level.  The Salamander Glacier covered an area of approximately 57 acre as of 1993.  Before Grinnell Glacier retreated significantly, it used to encompass The Salamander Glacier and the two become separate sometime before 1929.  The Salamander Glacier was measured at 42 acre in 2005, which is a 23 percent reduction since 1966.  Though only .10 mi in length, The Salamander Glacier is about .75 mi wide. Grinnell Point (7604 ft ) is located in the Lewis Range, Glacier National Park in the U.S. state of Montana.  Grinnell Point is an oft-photographed mountain, situated conspicuously just west of Swiftcurrent Lake across from the Many Glacier Hotel.  Grinnell Point is a subpeak of Mount Grinnell, which lies .21 mi to the west-southwest and is oftentimes misidentified as Mount Grinnell since that summit cannot be seen from the roads in the Many Glacier region.  Grinnell Point is named for George Bird Grinnell. Mount Grinnell is a peak located in the heart of Glacier National Park in the U.S. state of Montana in the Many Glacier region of the park.  Lying just east of the Continental Divide, the peak is flanked to the northwest by Swiftcurrent Glacier and to the south by Grinnell Glacier.  Mount Grinnell is named after George Bird Grinnell.  From the Many Glacier Hotel on Swiftcurrent Lake, the eastern arm of Mount Grinnell, known as Grinnell Point, hides the main summit.
Answer: Grinnell Glacier