Show grand coulee worlds number one dam grand coulee biggest dam in the world is now in action the columbia river which has been dammed is one ot of the swiftest and fiercest in the world and to curb it a barrier has been erected which is three quarters of a mile long and feet high the result win will be a lake miles long the irrigation of acres of land and sufficient electric power to supply an area five times the size ot of england boulder dam which harnesses the colorado river with all its collateral works was completed in 1935 it is thrown across a terrific gorge called black canyon which is 2000 feet wide and the lake behind it is miles long and took three years to fill so tremendous is the weight of water in this lake that geologists have suggested that it may cause a bending in the crust of the planet |