Lower Shoreface refers to the portion of the seafloor or sedimentary depositional environment

Sedimentary depositional environment

In geology, sedimentary depositional environment describes the combination of physical, chemical and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock...

 that lies below everyday wave base

Wave base

The wave base is the maximum depth at which a water wave's passage causes significant water motion. For water depths larger than the wave base, bottom sediments are no longer stirred by the wave motion above....

 (see also upper shoreface

Upper shoreface

Upper Shoreface refers to the portion of the seafloor that is shallow enough to be agitated by everyday wave action . Below that is lower shoreface.-Overview:...

). In this portion of the coastal environment, only the larger waves produced during storms have the power to agitate the sea bottom. Between storms, finer grained sediments accumulate on the seafloor, but during storms those sediments get suspended and moved around, resulting in a sedimentary structure form described as hummocky cross-stratification

Hummocky cross-stratification

Hummocky cross-stratification is a type of sedimentary structure found in sandstones. It is a form of cross-bedding usually formed by the action of large storms, such as hurricanes. It takes the form of a series of "smile"-like shapes, crosscutting each other. It is only formed at a depth of...

.