TASK DEFINITION: In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
PROBLEM: Passage: The northern segment of the fault runs from Hollister, through the Santa Cruz Mountains, epicenter of the 1989 Loma Prieta earthquake, then up the San Francisco Peninsula, where it was first identified by Professor Lawson in 1895, then offshore at Daly City near Mussel Rock. This is the approximate location of the epicenter of the 1906 San Francisco earthquake. The fault returns onshore at Bolinas Lagoon just north of Stinson Beach in Marin County. It returns underwater through the linear trough of Tomales Bay which separates the Point Reyes Peninsula from the mainland, runs just east of Bodega Head through Bodega Bay and back underwater, returning onshore at Fort Ross. (In this region around the San Francisco Bay Area several significant "sister faults" run more-or-less parallel, and each of these can create significantly destructive earthquakes.) From Fort Ross, the northern segment continues overland, forming in part a linear valley through which the Gualala River flows. It goes back offshore at Point Arena. After that, it runs underwater along the coast until it nears Cape Mendocino, where it begins to bend to the west, terminating at the Mendocino Triple Junction.
 Link Information: The Gualala River is a river on the northern coast of California. Most of the river is in Sonoma County, but a portion is in Mendocino County. The headwaters of the 40 mi river ( Answer: 40

SOLUTION: How long is the Gualala River?

PROBLEM: Passage: Vandenberg graduated from the United States Military Academy in 1951 (where Buzz Aldrin was one of his classmates). In 1953, Vandenberg was assigned to the 86th Fighter-Bomber Wing. Later he would serve as a flight commander with the 413th Tactical Fighter Wing and the 31st Tactical Fighter Wing. He graduated from the Air Command and Staff College in 1961, after which he was assigned to the 4th Tactical Fighter Wing. In 1963, Vandenberg was appointed Operations Officer with the 23rd Tactical Fighter Squadron. During the Vietnam War, Vandenberg commanded the 390th Tactical Fighter Squadron. Upon returning stateside he was assigned to The Pentagon to work in the Office of the Director of Plans. He would graduate from the National War College in 1969 and return to The Pentagon to work with the Joint Chiefs of Staff. In 1971, Vandenberg became commander of the 12th Flying Training Wing. Vandenberg was named Vice Commandant of Cadets at the United States Air Force Academy in 1972. He would serve as Commandant from 1973 to 1975, during which time he assumed the rank of brigadier general. From 1976 to 1979, Vandenberg served at Headquarters U.S. Air Force, first as Deputy Director of Plans, later as Director of Operations and Readiness, and finally as Assistant Deputy Chief of Staff for Operations, Plans, and Readiness. Vandenberg was ultimately named Vice Commander in Chief of the Pacific Air Forces. His retirement was effective as of January 1, 1981.
 Link Information: He would graduate from the National War College Answer:  Washington, D.C.

SOLUTION: Where is the National War College?

PROBLEM: Passage: Birks, a company that designs, manufactures and retails jewellery, timepieces, silverware and gifts, acquired the building in September 1912. The building was significantly reworked in 1912 to accommodate the jewellery store. The rework added distinctive Renaissance Revival palace facades designed by Percy Nobbs, featuring terracotta, granite, bronze and Tyndall stone. Above the third-floor openings are six terracotta medallions depicting the sources of the materials used by jewellers, with a seventh medallion on the north facade. These medallions depict turquoise (representing semi-precious stones), an elephant (representing ivory), a Kimberley Negro] searching for diamonds, a man diving for pearls, an oceanic wave delivering the riches of the sea (mother-of-pearl, coral and a tortoise shell), a precious metal-smelting gnome, and a silversmith surrounded by the tools of his trade. Above the medallions is a frieze depicting such characters and places as King Solomon, the Queen of Sheba, gates of Jerusalem, Hiram, king of Tyre, Negroes and an Indian, and the three wise men giving and receiving gifts. $150,000 of alterations to the ground-floor show-window area in 1951 included a granite base and Tyndall stone facings surrounding the solid bronze show windows, as well as corner columns and vestibule walls lined with Travertine marble. The building was the Winnipeg showpiece for Birks for nearly eighty years. By 1991, the basement, first, second and third floors had all been substantially altered by the Birks Company, leaving only the fourth floor of dormitories unaltered from the YMCA era. Birks continued in this building until the 1987 when it moved to Portage Place.
 Link Information: Terracotta is the term normally used for sculpture made in earthenware Answer: Tyndall Stone

SOLUTION:
Which of the materials that the palace facades featured was naturally formed?