Question: In which year did this American pioneering mountaineer and writer, after whom this scattering of glaciers and snowfields located on the southern flank of Mount Rainier in Washington was named, climb Mount Rainier?

Context paragraphs:
Ingraham Glacier: Ingraham Glacier is on the south-eastern flank of Mount Rainier, in the U.S. state of Washington.  The glacier is named for the Mount Rainier enthusiast Edward Sturgis Ingraham.  From the summit ice cap, Ingraham Glacier flows east between Gibraltar Rock, (12660 ft ), and Disappointment Cleaver and south of Little Tahoma Peak (11138 ft ), which divides it from the much larger Emmons Glacier to the north.  Descending southeast, it approaches the east flank of Cowlitz Glacier and the two glaciers nearly join at 6700 ft .  Meltwater from the glacier drains into the Cowlitz River.

Edward Sturgis Ingraham: Edward Sturgis Ingraham (April 8, 1852—August 16, 1926) was the first superintendent of the Seattle Public Schools, a noted mountaineer who climbed Mount Rainier 13 times, and a leader in the effort to establish Mount Rainier National Park.  Seattle's Ingraham High School is named in his honor, as is the Ingraham Glacier on Mount Rainier.

Kautz Glacier: The Kautz Glacier is a narrow glacier on the southern flank of Mount Rainier in Washington.  Named for August Kautz, who is sometimes credited for the first ascent of Mount Rainier, covers 1.8 sqmi and contains 7.8 billion ft (221 million m) of ice.  Upper Kautz Glacier extends south from the summit ice cap to Kautz Ice Cliff at about 11700 ft .  Immediately west of the main ice cliff, the glacier continues down Kautz Chute which terminates in another ice cliff just above the lower Kautz Glacier at 10800 ft .  Usually reached by a short descent from Camp Hazard at 11300 ft on Wapowety Cleaver, climbers following the Kautz Glacier climbing route ascend this chute to the upper glacier.

Mount Rainier High School: Mount Rainier High School is a secondary school in Des Moines, Washington, United States; named for Mount Rainier which can be seen quite well from the school on a clear day, which is rare in the fall and winter but very common in spring and summer.  Mount Rainier serves approximately 1700 students and has been active since 1957.  It was created to handle the overflow from nearby Highline High School, the district's first high school located in Burien, Washington.  The original, aging facility was replaced with a new building at the same location; it opened in September 2007.

Brentwood, Maryland: Brentwood is a town in Prince George's County, Maryland, United States.  The population was 3,046 at the 2010 census.  Brentwood is less than 1 mi away from Washington, D.C. The municipality of Brentwood is located just outside the northeast boundary of the District of Columbia and surrounded by the communities of Mount Rainier, Cottage City, North Brentwood, and the nearby Hyattsville.  Along the Route 1 Corridor, Brentwood is part of the Gateway Arts District.  Though Brentwood has its own fire department, it does not have its own police department, nor schools.  Therefore, it must rely on nearby Mount Rainier for access to schools and the general Prince Georges County Police Department for police.  The city of Mount Rainier, MD has two elementary schools in its neighborhood that children who live in Brentwood can use; Mount Rainier Elementary School and Thomas S. Stone Elementary School.  Both are part of the Prince Georges County Public School system and serve grades Pre-K through 6.

Pyramid Glacier: The Pyramid Glacier is actually a scattering of glaciers and snowfields located on the south-southwestern flank of Mount Rainier in Washington.  It covers 0.2 sqmi and contains 400 million ft (11 million m) of ice.  The glaciers lie at an elevation ranging from about 7000 ft to 9000 ft .  The Success Divide separates this glacier from the South Tahoma Glacier to the west.  Both the Success Glacier and lower end of the Kautz Glacier border this glacier on the eastern side.  Meltwater from the glacier drains into the Nisqually River.

Mowich River: The Mowich River is a river in the U.S. state of Washington.  Its watershed drains a portion of the western side of Mount Rainier, part of the Cascade Range.  The river has two main headwater branches, the South Mowich River and the North Mowich River.  The South Mowich is significantly larger and sometimes considered the main river.  The Mowich and its tributaries drain several of Mount Rainier's glaciers.  The upper portion of its watershed is contained within Mount Rainier National Park.  The river flows into the Puyallup River in the foothills west of Mount Rainier.

Cowlitz Glacier: The Cowlitz Glacier is on the southeast flank of Mount Rainier in the U.S. state of Washington.  The body of ice covers 1.3 sqmi and has a volume of 6 billion ft (170 million m).  The glacier starts at an elevation of 10700 ft and flows southeast.  An adjacent glacier, the Paradise Glacier, is connected to this glacier on its southwest margin.  As it flows down the slopes of Mount Rainier it nearly meets up with the Ingraham Glacier and during the Little Ice Age, which ended around the year 1850, the two glaciers shared a common terminus.  Meltwater from the glacier drains into the Cowlitz River.

Van Trump Glacier: The Van Trump Glacier is actually a scattering of glaciers and snowfields located on the southern flank of Mount Rainier in Washington.  Named after P. B. Van Trump, who was part of an early ascent of Mount Rainier, the glacier covers 0.2 sqmi and contains 500 million ft (14 million m) of ice.  The glacier is located between the Wilson Glacier to the east and the Kautz Glacier to the west.  The elevation of the scattering ranges from 7000 ft at the lower end to 9800 ft on the upper reaches of the glacier.  Meltwater from the glacier drains into the Nisqually River.

P. B. Van Trump: Philemon Beecher Van Trump (1839–1916), also known as P. B. Van Trump, was an American pioneering mountaineer and writer who lived in the state of Washington.  He is best known for the first ascent of Mount Rainier in 1870.

Supporting paragraphs: Van Trump Glacier P. B. Van Trump
Answer: 1870