Final answer:
The cerebral cortex is composed of a thin layer of gray matter, not white matter, and is responsible for higher cognitive functions such as memory and language, as well as sensory and motor processing.
Step-by-step explanation:
The generalization that does not describe the cerebral cortex is "Mainly composed of white matter." The cerebral cortex is actually the thin layer of gray matter that forms the outermost layer of the cerebrum, responsible for higher cognitive functions like memory, learning, language, and conscious perception. The cortex features gyri and sulci's patterns which delineate specific regions for processing sensory and motor functions. It is divided into regions such as the frontal, parietal, temporal, and occipital lobes, each with specialized roles, including the prefrontal area's involvement in executive functions and attention. The white matter lies beneath the gray matter and is composed mainly of myelinated axons facilitating communication between different brain regions.