The consolidation of Colombia as a nation-state has faced a major obstacle in the country's geography, the main topographical feature of which is the Andean mountain range. Before the economic crisis of the early 1930s Colombia had undergone two decades of export-led growth. The world depression put an end to this boom, dubbed by the future Liberal president, Alfonso Lopez Pumarejo, the 'dance of the millions'. Proclaiming a revolucion en marcha, Lopez offered a broad reformist and welfare programme within the framework of a liberal democracy with increased political participation. The balance of power within the Liberal Party shifted from the reformists to the consolidators led, after Olaya's death in 1937, by Eduardo Santos, who reassured an upper class alarmed by the populist techniques of Lopez and Gomez. Eduardo Santos epitomized a cautious brand of Liberalism which was so acceptable to the Conservative propertied classes that they did not field a rival candidate in the 1938 presidential election.