WASHINGTON — For many who helped dedicate the new Martin Luther King Jr. Memorial on Sunday, the towering granite monument is a stark reminder that the civil rights leader’s dream of social and economic justice has yet to be realized.

In many ways, the ceremony was a passing of the torch to a younger generation with speeches marked by fierce rhetoric over the nation’s economic disparities.

Thousands gathered at the memorial site, some as early as 5 a.m., to hear President Barack Obama, King’s children and other civil rights leaders. Speaker after speaker invoked King’s “I Have a Dream” speech from 1963 to challenge others to carry on his fight.

“Yes, my father had a dream. It was a dream, he said, that was deeply embedded in the American dream,” said King’s son Martin Luther King III. “The problem is the American dream of 50 years ago … has turned into a nightmare for millions” who have lost their jobs and homes.

The nation has “lost its soul,” he said, when it tolerates such vast economic disparities, teen bullying, and having more people of color in prison than in college.

His sister, the Rev. Bernice King, reminded the crowd that just before her father’s assassination in 1968, he was mobilizing a poor people’s campaign to occupy the nation’s capital until the economic system changed.

She said the postponement of an earlier dedication because of Hurricane Irene that was planned on Aug. 28, the 48th anniversary of her father’s “Dream” speech, may have been an act of God.

“Perhaps the postponement was a divine interruption to remind us of a King that moved us beyond the dream of racial justice to the action and work of economic justice,” she said. “Perhaps God wanted us to move beyond the ‘dream’ into action.”