1963

During the period between 1960 and 1964, Mitchell moved away from the all-over style and bright colors of her earlier compositions, instead using sombre hues and dense central masses of color to express something inchoate and primordial. The marks on these works were said to be extraordinary: "The paint flung and squeezed on to the canvases, spilling and spluttering across their surfaces and smeared on with the artist's fingers." The artist herself referred to the work created in this period of the early 1960s as "very violent and angry," but by 1964 she was "trying to get out of a violent phase and into something else."

https://en.wikipedia.org/wiki/Joan_Mitchell

Untitled (triptych)
1963
Oil on canvas
162 x 325 cm
The Museum of Modern Art
New York