Final answer:
Small sediments get deposited in low-energy depositional environments where the water's movement is not strong enough to carry them away. These environments can be identified by characteristics such as graded bedding and rock color, indicating the amount of oxygen present during sediment deposition.
Step-by-step explanation:
In a low-energy depositional environment, even small sediments can get deposited. This occurs because the energy available to transport sediment is insufficient to carry smaller particles away, resulting in their accumulation. Low-energy environments are often associated with areas where water movement is minimal, such as the bottoms of lakes, deep marine settings, or swamps where slow-moving or still waters allow for fine sediments to settle out of suspension.
Environments such as coastlines can be high energy, characterized by wave action capable of transporting well-sorted gravel and sand. Conversely, fine sediments like clay or silt typically settle in more tranquil water bodies, as seen with the terminal velocity in lakes. These low-energy environments are crucial for the process of graded bedding, where a single sedimentary layer shows a gradation in particle size, with coarsest particles at the bottom and finer upward, indicating a decrease in transport energy over time.
Differentiating these environments can be challenging, but the sedimentary rocks' color may offer clues to the original depositional conditions. For instance, black or dark gray can signify anoxic (oxygen-poor) deep marine or swamp environments, while green or light gray might imply a low oxygen shallow marine setting. In contrast, red, orange, brown, or yellow indicate oxygen-rich environments, like rivers or deserts.