[OE] AERIAL SHOTs from helicopter of spring break-up on Mackenzie River, shadow of helicopter is visible on some shots. Several MCSs of break-up, moving ice grinding into river bank, breaking trees and moving boulders, shot from helicopter hovering low near river bank. MCSs of massive ice blocks swept away from river bank by strong waters. AERIAL SHOT of ice floe breaking into blocks on Mackenzie River. Several shots from different angles of moving ice grinding into river bank, breaking trees and moving boulders. MS of point where tributary river meets frozen Mackenzie River. MCS of ice blocks moving downstream, seen from river bank.