The rains began in the summer of 1926. By Christmas Day that year, the Mississippi had reached historic levels, leaving 27,000 square miles of the American South under nearly 30 feet of water. Then, the levees broke. 145 of them, to be exact. 246 perished, and almost 630,000 predominantly African-American people were displaced. And it only kept pouring.

The Great Mississippi Flood of 1927 had such catastrophic consequences that you would expect its film rendition to have CGI waves engulfing CGI people living in CGI houses. Instead, the film that charts this remarkable natural disaster is “The Great Flood,” the third feature-length documentary by esoteric director and multi-media artist Bill Morrison.

Morrison, who attended last Sunday’s screening at The Whitney Humanities Center wearing jeans and a black baseball cap, has the general appearance of an artist who has decided long ago to let their work and not their personal appearance be of main interest. What he lacks in personal fashion, Morrison soon makes up for with his inventively vague introduction of the film as “an elliptical work,” that aspires to put the viewer “on a raft of visual information.” Elliptical work? Raft of visual information?  Looking around at the crowd of fifteen or so other screening-goers, I wondered: What have I gotten myself into? But then the lights vanished, someone coughed, and the first, grainy image flashed on screen.

Using a combination of decayed newsreels and aerial footage, Morrison relates the cataclysmic flood without so much as setting a scene, shooting an original frame, or even voicing a word. But the film is by no means silent; Morrison’s assemble of vintage footage is accompanied by an original score crafted by the guitarist and composer, Bill Frisell and recorded live by Frisell, Ron Miles, Tony Scherr and Kenny Wollesen. While Morrison’s imagery tells the external story of the flood, Frisell’s score demonstrates its musical implications.

A mix of what Morrison called “rhapsodic arias” and good old blues, Frisell’s score reflects the forced migration of roughly 200,000 mainly African-American sharecroppers as well as the musical transformation that followed them north. Among those who made the trip were renowned Delta Blues artists, Big Joe Williams and Freddie Spruell. Their musical style, which included explosive guitar parts combined with poetic storytelling, would soon inspire the next generation of blues artists in Chicago, where both settled after the flood of ‘27. On a broader level, the influx of African-American artists to Northern cities created a more centralized market for the distribution of recorded blues music, which had once been an almost exclusively live genre. This transition laid the foundation for the growth of blues from a regional dialect of country music into the musical soil that sprouted perhaps the most influential musical genre of the 20th Century: rock and roll.

Frisell’s score and Morrison’s imagery share a tone surprisingly absent of misery in a film that deals with such tragedy. In steady, unhurried shots, the first rains of 1926 are shown swallowing up and soothing the land as though the water were a liquid blanket and not an unstoppable wave of destruction. The melodic guitar and trumpet piece that accompanies these images only furthers the odd sentiment that, somehow, this flood is something worthy of reverence, not mourning. And most startling of all are Morrison’s depictions of the people affected by the flood: contrary to what you might expect when watching a film about a natural disaster, there are no scenes of families grieving their lost homes.

Despite the optimistic tenor of the film, Morrison is no sadist. He does not delight in the leveling of entire towns or in the collective sorrow of a mainly African-American population affected by the flooding. Instead, he conveys its liberating effect on its survivors. With the inhumane practice of sharecropping as the backdrop for the film, Morrison portrays the flood as a catalyst for social change of biblical proportions. As the director mentioned in his post-screening remarks, “the flood gave people working on sharecropping plantations an opportunity to leave. Everything was destroyed and so no one was making any money anyway.” And leave they did: the second half of the film follows the subsequent migration up from the Mississippi Delta. The footage, which earlier had been marked by a constant level of decay, becomes clearer and surer of itself, as if a veil has lifted. So, too, the tentative guitar strumming of the first part of the film is replaced with driving, momentous chords as the Delta Blues become the Chicago Blues and, in so doing, presage rock and roll.

After a whirling sequence in which images of folks boarding trains are overlaid on a reproduced map, the camera finally settles on a single African-American woman. The sense of renewal is palpable. Morrison has been building this ethos since the first shots of the movie, those that show the flood rushing in gracefully, a liquid path to freedom from the horrors of sharecropping. This woman is, finally, a microcosm of Morrison’s conception of the flood as a constructive event: In the face of destruction, she does not despair. She dances.