What was Georgia O'Keeffe's first major abstract series, begun in 1915?

Georgia O'Keeffe's first major abstract series, begun in 1915, was a group of charcoal drawings.

These drawings marked a decisive break from the more conventional representational art she had been taught. Instead of depicting recognizable objects, O'Keeffe used lines, curves, and tonal contrasts to explore visual expression. The series became important evidence of her early modernist experimentation.

The drawings were made while she was teaching in South Carolina. She sent some of them to her friend and former classmate Anita Pollitzer, who showed them to Alfred Stieglitz in New York. Stieglitz exhibited them in 1916, helping bring O'Keeffe to wider attention.

The phrase does not mean that she abandoned drawing permanently. Drawing remained fundamental to her practice, even as she later became famous for paintings of flowers, bones, buildings, and landscapes.