Which geological theory aligns with the idea of gradual changes over time?

The theory that aligns with the idea of gradual changes over time is uniformitarianism. This principle, often summarized by the phrase "the present is the key to the past," suggests that the geological processes we observe today, such as erosion, sedimentation, and volcanism, operated similarly in the geological past. This perspective emphasizes that slow, continuous processes can lead to significant changes over extended periods.

Uniformitarianism contrasts with catastrophism, which posits that Earth's features were primarily shaped by sudden, intense events, such as natural disasters like floods or volcanic eruptions. While both theories are important in understanding Earth's history, uniformitarianism focuses on gradual processes rather than abrupt changes.

Disconformity refers to a specific type of unconformity in geology and is related to time gaps in sedimentary rock layers. The law of superposition, on the other hand, is a principle that states in undeformed sedimentary rock layers, the oldest layers are at the bottom and the youngest are at the top, but it does not deal with the nature of changes over time as uniformly as uniformitarianism does. Thus, uniformitarianism is the correct theory that emphasizes gradual geological change.