[CholeraJoe]

but that a rock would have to be at least 3 feet (1 meter) in diameter to create a hole that size.

To make a 9 m crater? Maybe, if you kick it out the door of a plane at 10,000 feet and it impacts going at terminal velocity, about 200 mph.

Objects coming from outer space are traveling much faster when they enter the atmosphere, about Mach 6 or 4500mph. At that velocity, a fist-sized object could make that size of crater.

[stormer]

Your speed is off by a magnitude.

I haven’t entered the info, but here’s an interesting link: http://www.lpl.arizona.edu/tekton/crater_p.html