What may produce a less distinct trace of the profile of the seabed?

A less distinct trace of the seabed profile can occur when sound penetrates softer seabed materials. Softer materials, such as silt or clay, tend to absorb sound energy rather than reflecting it back. This absorption can lead to less distinct echoes and a more blurred representation of the seabed features, making it difficult to identify and differentiate between subtle changes in topography.

In contrast, harder seabed materials, such as rock or gravel, would typically provide clearer reflections of sound waves, resulting in sharper and more defined traces of the seabed profile. Similarly, high frequency sounds generally produce clearer profiles due to their ability to provide more detailed information about smaller features on the seabed, as they have shorter wavelengths that can detect finer details. Low frequency sounds, while capable of penetrating deeper into the seabed, do not effectively map features due to their longer wavelengths, which may overlook smaller irregularities.