Marsden Hartley made his earliest mark on the art of the 20th century with his move to Berlin in 1913 at age 36. There he captured the militaristic pageantry of the Prussian capital in colorful, dynamic paintings that were thoroughly modernist in form and spirit. But the horrors of World War I changed everything, including Hartley's appetite for the "pomp and circumstance of war," as the New York reviewer Henry McBride termed it in a 1918 review of the artist's paintings at Alfred Stieglitz's 291 Gallery.

The crisis of confidence in the modern world was felt throughout the avant-garde, not least by Hartley. "I am really tired out spiritually by the loss of illusions," he said in a 1917 letter to Stieglitz. By the next summer, he was in Taos, New Mexico, a guest of his friend and patron Mabel Dodge. Later he set himself up in Santa Fe. "I am an American discovering America," he wrote in a 1918 essay for El Palacio magazine, an essay that is reproduced as an appendix to the catalogue for the current show at Alexandre Gallery in the Fuller Building in Manhattan, "Marsden Hartley, New Mexico 1918-20: An American Discovering America."

This focused exhibition includes about a dozen landscapes and still lifes made during Hartley's first sojourn to the great American Southwest. Examined together, in the serene precincts of the gallery, these paintings and pastels demonstrate Hartley's remarkable turn from urban hurly-burly to a timeless desert pastoral. His paintings from this period clearly embody notions of Ralph Waldo Emerson's transcendentalist philosophy, which sought a path to God through a personal, subjective understanding of primal nature.

Hartley's focus on the desert landscape makes this notion palpable, in paintings that look fresh enough to have been made yesterday. Many of the works are clearly inspired by Cézanne's landscapes, with the drawing in blue line filled in with individual strokes and patches of paint -- though the color scheme is transformed from the greens of the French countryside to the pinks, yellows, mauves and browns of New Mexico. Hartley knew Cézanne, of course; in 1926 he would even go so far as to rent a studio in the South of France that had been Cézanne's.

The Whitney Museum's large Landscape New Mexico from 1919-20 -- confusingly, most of the landscape pictures carry this title, or a variation on it -- is perhaps the most dramatic and muscular, looking down at a horizontal ravine with swollen mountains rolling in the distance under a lively blue sky. The 1919 New Mexico Landscape from the Curtis Galleries in Minneapolis is more reserved, with a tiny farmhouse nestling beneath tiers of pink and green hills.

The Weisman Art Museum's New Mexico Landscape, also from 1919, is arguably Hartley's magic mountain, a visionary Mont St. Victoire set in the Southwest. Still another painting in the show, the 1919 New Mexico Landscape, is done on newsprint mounted on canvas, and bits of text are still visible through the paint -- reporting on the 1918 Armistice. For this picture, Hartley used not the Cézannesque blue outline but an expressionistic, Beckmann-like black, limning a powerful scene of pulsing blood red mountains that rise from green and orange plains.

The show also includes several still lifes, including Volupté (1919), a bouquet of pink lilies in a double-handled blue vase wreathed in swaddling on a tipped-up table, and Cerise Cactus (ca. 1918), in which a viridian cactus with spiky pink flowers is bound with two coils of yellow twine.

Hartley, who was born in 1887 and died in 1943, was intensely bohemian -- in photos he resembles Ichabod Crane -- who lived a remarkably peripatetic life of painting, poetry, writing and the arts. Looking back, his world seems to be one of boundless artistic possibility, marked always by strong feelings and a determined commitment to his work.