Final answer:
A coastal area is classified as emergent if it shows signs of aggradation, the presence of emergent vegetation, and geological features indicating geological uplift or sea level fall, such as marine terraces, wave-cut benches, and historical clam shell beds above current tide lines.
Step-by-step explanation:
To classify a coastal area as emergent, you would look for certain observable features. Emergent coastlines are typically characterized by the presence of aggradation, where the land features such as beaches, dunes, and salt marshes show growth or elevation above sea level.
This could be due to geological uplift or a drop in sea level. Signs of emergence could also include emergent vegetation, with plants that are rooted in the soil yet their leaves, stems, and flowers extend above the water's surface. Moreover, features like marine terraces, which are level platforms with a steep face, may indicate a historical sea level higher than the current level, suggesting the land has risen.
Another indication is the presence of wave-cut benches, which are flat or gently sloping areas that extend from the shore into the water and are formed by wave erosion when the sea level was higher. The existence of old clam shell beds found above the current high tide line could also suggest the area was once underwater and has since emerged. Observations of sediment patterns, such as those found in sediment cores described in geological time-lapses, can provide evidence that sea level has fallen or the coastline has risen.