Revolution was a common occurrence because large vacuums of power usually followed what has been deemed "White Flight," or the emigration of Europeans out of Africa. During colonial periods, European government strove to maintain a small, strong, and central hold of power limited normally to white elites or native Africans who allied closely with those white elites. So when the European powers left Africa, many competing seats of power (traditionalists, military men, religious leaders) all sought to gain and maintain that central hold of power that had existed since the Berlin Conference in the late 1800s.
Angular unconformity is an unconformity where horizontally parallel strata of sedimentary rock are deposited on tilted and eroded layers, producing an angular discordance with the overlying horizontal layers. The whole sequence may later be deformed and tilted by further orogenic activity.
C: Landslide victory for Andrew Jackson