Bolides Falling into Water: Not Such a Simple Crater
Alamo Impact Crater Formation
Complex craters, like the Alamo Impact crater, are associated with large bolide impacts in a marine setting. They are larger in diameter and shallower in depth compared to simple craters. The increased impact force creates steep crater walls that collapse downward along normal faults, decreasing the depth and pushing up the center to form a central uplift. Further uplift of the crater center is due to crustal rebound of the Earth's surface in response to the large force.
Think of the Earth as a large bouncy ball. If you were to press your finger into the ball, much like an incoming bolide crashing into the Earth, the ball depresses inwards and forms a crater at your finger's location. As you remove your finger, the internal strength of the ball pushes outwards and rebounds to fill the space your finger once occupied. This same concept applies to the formation of the central uplift. A variety of high rims and low troughs also form throughout complex craters. These low troughs can act as channels, transporting impacted rock throughout the crater.