Step-by-step explanation:
A combination of the following rock features would convince you that a particular rock layer is of sedimentary origin:
Layering: Horizontal or roughly horizontal layering is a key characteristic of sedimentary rocks, whereas volcanic rocks often have a more chaotic texture.
Fossils: The presence of fossils, such as shells or plant remains, is a strong indicator of sedimentary rock.
Grains and clasts: The presence of distinct grains or clasts (fragments of other rocks) in the rock layer is a hallmark of sedimentary rocks. The size, shape, and sorting of these grains can also indicate the transportation and depositional processes that formed the rock layer.
Rock composition: Sedimentary rocks often contain minerals, such as quartz and calcite, that are not commonly found in volcanic rocks.
Stratification: The presence of cross-bedding, ripple marks, or other structures that suggest the rock layer was laid down gradually over time, is a strong indicator of sedimentary rock.
By combining these features, a geologist can make a strong case for the sedimentary origin of a particular rock layer.