Input: Read this: Glacial abrasion is commonly characterized by glacial striations. Glaciers produce these when they contain large boulders that carve long scratches in the bedrock. By mapping the direction of the striations, researchers can determine the direction of the glacier's movement. Similar to striations are chatter marks, lines of crescent-shape depressions in the rock underlying a glacier. They are formed by abrasion when boulders in the glacier are repeatedly caught and released as they are dragged along the bedrock.
Question: What is formed when glaciers crush boulders?

Output: unanswerable

Input: Read this: Writings in Estonian became significant only in the 19th century with the spread of the ideas of the Age of Enlightenment, during the Estophile Enlightenment Period (17501840). Although Baltic Germans at large regarded the future of Estonians as being a fusion with themselves, the Estophile educated class admired the ancient culture of the Estonians and their era of freedom before the conquests by Danes and Germans in the 13th century.
Question: Who conquered the ancient Germans?

Output: unanswerable

Input: Read this: Some types of energy are a varying mix of both potential and kinetic energy. An example is mechanical energy which is the sum of (usually macroscopic) kinetic and potential energy in a system. Elastic energy in materials is also dependent upon electrical potential energy (among atoms and molecules), as is chemical energy, which is stored and released from a reservoir of electrical potential energy between electrons, and the molecules or atomic nuclei that attract them.[need quotation to verify].The list is also not necessarily complete. Whenever physical scientists discover that a certain phenomenon appears to violate the law of energy conservation, new forms are typically added that account for the discrepancy.
Question: old forms are typically added that account for what?

Output: unanswerable

Input: Read this: In ancient Somalia, pyramidical structures known in Somali as taalo were a popular burial style, with hundreds of these dry stone monuments scattered around the country today. Houses were built of dressed stone similar to the ones in Ancient Egypt. There are also examples of courtyards and large stone walls enclosing settlements, such as the Wargaade Wall.
Question: What is a notable stone wall built in ancient Somalia?

Output:
the Wargaade Wall