Answer to Question 1
Answer: One of the things that define objects in the three states of matter is how much thermal energy they have. The more thermal energy molecules have, the harder they vibrate, and the farther they move apart. As a result, when substances are warm, the molecules are farther apart than when that same substance is cold. When a mineral such as halite is dissolved in warm water, for example, there is more room between the water molecules for the halite molecules. However, when the temperature of the water drops, the water molecules move closer together, decreasing the room available for the dissolved mineral molecules. In the current example, this would force the precipitation of halite.
Answer to Question 2
Answer: Limestone forms in shallow marine environments, so without any additional information, it can be inferred that large areas of the United States were once covered with a shallow sea. However, limestone is often formed through the secretion of CaCO3 by marine organisms such as clams and corals, so the primary method of mineral formation is minerals formed by biological processes. This inference would be supported by the presence of marine fossils.