It's Really Quite Simple: Crater Basics
Alamo Impact Crater Formation

Simple craters are associated with small bolide impacts in terrestrial environments, which generate a small force on Earth's surface. They are characterized by a uniformly concave-upward shape and are smaller in diameter, yet deeper when compared to complex craters. This is because the small force is not enough to affect the walls of the crater or cause a large crustal rebound of the Earth's surface. Thus, simple craters lack central uplifts and rim terraces. One of the most well known simple craters is Meteor Crater in northern Arizona.

Simple Crater Gosses Crater, Australia

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