What is the process by which unconsolidated materials are converted into solid rock?

The conversion of unconsolidated materials, such as sediment, into solid rock is known as lithification. This process involves several key steps, primarily cementation and compaction, which work together to solidify loose materials into a more stable geological formation.

During lithification, the accumulation of sediments gets compacted over time due to the weight of overlying materials, which reduces the space between the particles. In addition to compaction, the minerals dissolved in water can precipitate out and fill the gaps between sediment particles, effectively cementing them together. Together, these mechanisms transform loose sediments into solid rock, which can take various forms, such as sandstone or limestone, depending on the composition of the original materials.

The other processes listed serve different functions in the geological cycle: weathering refers to the breakdown of rocks and minerals at the Earth's surface, erosion involves the transportation of weathered materials from one location to another, and compaction is a part of lithification but does not encompass the entire process of turning sediments into rock. Thus, lithification is the comprehensive term that accurately describes the entire conversion process.