What is a famous monument in Texas that starts with the letter x?

How many miles of passageways have been mapped and surveyed at mammoth cacves? How do marine life be affected by constructions of dams? One of the huge bodies of salt water that make up about two thirds of the surface of the earth called? What is the average love-seat depth? How is cutting trees down help forests? What did Abagail Adams ask her husband John Adams? How much did London bridge cost to construct? Which body of water separates India from Thailand and Malaysia? What is the distance from Milwaukee Wisconsin to Yellowstone National Park? How much do the earth's land surface do deserts cover? What was the name of the contested fur-rich farmland where the French would trade manufactured goods to the American Indians for fur? When did Lake Erie catch fire? What zone do crabs live in? What does the classic memory aid HOMES stand for? What separates the gulf of Mexico and the pacific ocean? Who did Shah Jahan marry? In which direction does the gulf stream head? What are oceanic-oceanic and oceanic-continental subduction boundaries? What is meant by the term Mediterranean? How do you make a model of a portcullis?