As volcanologists like Tamsin Mather are apt to make clear, not all volcanoes are the same. Água de Pau in the Azores Islands, for example, is a stratovolcano, a conical volcano built up by many layers of hardened lava and tephra. Methana in Greece, ______ is a lava dome, a circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano.

Generally, sleek vehicles are more aerodynamic than bulkier ones. The streamlined nose of the F-104 Starfighter jet, ______ helps it glide through wind with relative ease, while a boxy pickup truck encounters more wind resistance, making it less aerodynamic.

When ordering the branches of the Yukon River system by Hack's method, one begins with the riverway's lowest point, the Yukon River. ______ when using Strahler's method, one begins at the top of the river system, with the Kanuti River and other tributaries fed by the riverway's source, Alaska's Llewellyn Glacier.

Formerly known as the Indiana Territory, Indiana was granted statehood by a vote of the US Congress on December 11, 1816, making Indiana the 19th US state. By comparison, as one of the nation's original thirteen colonies, Connecticut became a state when it ratified the US Constitution on January 9, 1788. ______ New York attained statehood by ratifying the Constitution, becoming the 11th US state on July 26, 1788.

From mountains to monuments, deserts to rainforests, and isolated islands to teeming cities, the sites on UNESCO's World Heritage List are chosen because they hold cultural or natural value that the organization wishes to preserve for future generations. ______ in 2008, UNESCO recognized the importance of France's Lagoons of New Caledonia, making up one of the largest reef systems in the world, by adding them to the list as a natural heritage site.