The supports are fixed to the wall of the dam in order to help counteract the force of the water on the dam. Buttress style dams are built across wide valleys that do not have a solid bedrock foundation. Bedrock is solid rock that makes up the upper part of the earth’s crust. Bedrock can be made from sedimentary, igneous, and metaphoric rock origins. Buttress dams require extensive steel framework and labor. As a result, buttress style dams are expensive to construct and are seldom built today. Arch style diversion dams are designed using an arch shape with the top of the arch facing upstream. The arch shape provides extra strength to counteract the force of the water. Arch style dams are generally constructed in narrow canyons. Arch style dams are commonly made from concrete. To ensure the dam’s integrity, a solid contact between the bedrock foundation and the dam’s concrete base is required. The dome style dam is a type of arch dam. The dome style dam curves in both the horizontal plane and vertical plane. The arch style dam only curves in the horizontal. Gravity style diversion dams are built to non counteract the force of the water pushing on the dam by building a dam with enough weight to withstand the force. Gravity dams are commonly constructed using masonry or cement. The foundations of the gravity dams are generally constructed on top of a solid bedrock foundation. However, gravity dams can be built over unconsolidated ground as long as proper measures are put in place to stop the flow of water under the dam. If water were to get under the dam, the dam could fail.