Randomized Controlled Studies: This is a study in which 1) There are two groups, one treatment group and one control group. The treatment group receives the treatment under investigation, and the control group receives either no treatment (placebo) or standard treatment. 2) Patients are randomly assigned to all groups.
winds that blow in a steady direction can move a dune. such wind will consistently pick up sand from one side and deposit it to a other side. this causes the entire dune to s â¦ lowly move in the direction if the wind.
Longshore drift moves material along the coastline. 1  A spit forms when the material is deposited. 2  Over time, the spit grows and develops a hook if wind direction changes further out. 3  Waves cannot get past a spit, which creates a sheltered area where silt is deposited and mud flats or salt marshes form.