The contact between the shale, which dominates the bottom part of this sedimentary sequence, and the sandstone, which dominates the upper part, is best described as: 
Definitions:
Subliminal Messages
Messages that are designed to pass below the normal limits of perception and are thought to be capable of influencing an individual's thoughts or actions unconsciously.
Post-Hypnotic Suggestions
Instructions given to a person under hypnosis that are intended to be acted upon after they have emerged from the hypnotic state.
Genetic Differences
Variations in the DNA among individuals or populations, contributing to the diversity in physical traits, susceptibilities to diseases, and behavioral tendencies.
Dopamine
A neurotransmitter involved in many functions, including motivation, pleasure, cognition, memory, learning, and fine motor control.
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