The Delmarva Peninsula on the East Coast of the United States is divided between Maryland, Delaware and Virginia. The northern part of the peninsula has many small Carolina Bays, but larger bays are also encountered. The bays in Delmarva tend to be more circular than elliptical, and the pattern of the bays looks like a shotgun blast.
The southern part of the Delmarva peninsula belongs to Virginia. The Carolina Bays along this narrow strip of land are circular. This image near Mappsville, Virginia shows large bays with diameters of approximately 1.3 kilometers. Delmarva does not have deep sandy soil because thirty-five million years ago, a meteorite struck the Chesapeake Bay and created a tsunami that washed away the loose surface sand of the Delmarva peninsula. The shallow depth of unconsolidated material in Delmarva made it impossible to create inclined conical cavities, and this resulted in circular bays.
The following photographs show an experiment to test the impact of an ice projectile on shallow depth of viscous material. The target consisted of equal parts of sand and pottery clay with enough water to have the consistency of bricklayer's mortar. The depth of the material was controlled by burying a pie tin with the viscous mixture.
An oblique impact on a target that constrains the depth of the medium results in a circular structure. When the depth of the medium is not constrained, and impact creates an inclined conical cavity that becomes an elliptical bay by viscous relaxation.