Why is there a massive gap in the geological rock layers of the Grand Canyon?

The Grand Canyon's geological record reveals significant time gaps due to unconformities, which are major erosion surfaces separating rock layers. These gaps represent periods where vast amounts of material were removed by erosion, or where little to no deposition occurred. Consequently, rock formations of considerably different ages are separated by only a thin surface, indicating a vast unconformity in time.1

The canyon's geologic history includes ancient Archean granite and schist over 2.5 billion years old at the bottom, overlain by Proterozoic limestones, sandstones, and shales older than 540 million years. Paleozoic rock strata, representing over 300 million years of deposition, form much of the canyon walls. Notably, Mesozoic rocks that should lie above these have been entirely eroded away, creating a substantial gap in the geological record.1