Blackstone Glacier starts at an elevation of about 5,000 feet (1,500 m) in the Kenai Mountains and flows generally north for 7 miles (11 km) and terminates at tidewater at the head of Blackstone Bay, about 87 miles (140 km) west-southwest of Valdez and 8 miles (13 km) south of Whittier, Alaska. The local name was reported in 1899 by Walter C. Mendenhall of the U.S. Geological Survey. Blackstone Bay is a fjord on the Kenai Peninsula in western Prince William Sound that trends northeast for 13 miles (21 km) to the entrance of Passage Canal, about 10 miles (16 km) east-northeast of Whittier. The glacier and bay are named after Charles A. Blackstone, a gold prospector from Seattle. The bedrock exposed by the retreating glacier is partially metamorphosed sedimentary rocks of the Valdez Group which is part of the Southern Margin composite terrane that extends for more than 1,056 miles (1,700 km) along the southern coast of Alaska. The Valdez group consists primarily of complexly deformed greywacke, siltstone, and shale that formed during the Late Cretaceous from deposits by turbidity currents in a deep oceanic trench along a subduction zone, and were subsequently accreted to the margin of North America.

In 1896, Charles A. Blackstone left Seattle on a steamship with 250 other men hoping to find gold in Alaska. On the trip north, he teamed up with Charles Botcher and J.W. Malinque and made plans to prospect near the Hope and Sunrise mining camps in Turnagain Arm. When they landed at Seldovia in Kachemak Bay, near the mouth of Cook Inlet, they learned that traveling to Turnagain Arm would be very difficult because of the strong tidal currents and shallow water. It took them most of the summer to reach the Sunrise camp, and the prospecting season mainly was over. In March 1897, out of funds and supplies, the dispirited group decided to return to Seattle. They planned to walk from Sunrise over Portage Pass to Passage Canal on Prince William Sound where they would board a ship. The route was arduous but marked and well-known by other prospectors. However, the group encountered severe winter conditions in the mountain pass, probably became disoriented in a snowstorm, and missed a critical turn. A search party later discovered the remains of Charles Blackstone high in the mountains and far from the route on what is now named Blackstone Glacier. He had left a note describing their ordeal that led to the death of Botcher and Malinque from the cold on April 1, 1897, and Blackstone died sometime after April 4 when the note was written. The bodies of Botcher and Malinque were never found.

In 1909, when Ulysses S. Grant and Daniel F. Higgins visited the fjord, Blackstone Glacier was a massive ice field that surrounded the head of Blackstone Bay and discharged at least 10 separate ice streams. Since then the ice field has thinned and separated into individual glaciers with only Blackstone and Beloit Glaciers, both located at the head of the bay, reaching tidewater. Blackstone Glacier has a length of 7 miles ( km), an area of 7,900 acres (3,200 ha), an accumulation area of 7,166 acres (2,900 ha), an ablation area of 494 acres (200 ha), and a terminus width of 1,640 feet (500 m). There is evidence that Blackstone Glacier historically extended to the north end of Willard Island, about 5.5 miles (9 km) northeast of the current glacier terminus. A conspicuous submarine terminal moraine, part of which is exposed under most tidal conditions, connects Willard Island in the middle of Blackstone Bay with the eastern shore. Grant and Higgins suggested that the moraine predates the early 18th century. Read more here and here. Explore more of Blackstone Glacier and Blackstone Bay here: