[SunkenCiv]

They make a big kaboom. A rock a mile across (depending of course on the velocity) can deliver more pop that all the nuclear arsenals put into a pile and set off simultaneously. The Meteor Crater / Barringer Crater in Arizona was formed by a rock about 160 feet across (about 1/33rd of a mile, hence, other things being equal, about 1/35937 of a mile diameter rock, that's 33 in three dimensions). Boom.

The crater stretches 1200 meters across and 170 meters deep, with the rim of the crater rising 45 meters above the surrounding landscape. The area around the impact site is tinted red with oxidized iron from the nickel-iron meteor which impacted there almost 50,000 years ago. | University of Iowa

[SunkenCiv]

Your view, if you would — the Arizona crater is 1200 meters across, if a mile-wide rock hit, would the crater be approximately 33^2 in area compared with the Barringer Crater?

http://www.freerepublic.com/focus/chat/3735815/posts?page=32#32

[SunkenCiv]

Oops, silly me, from the linked page in #30:

Impact:Earth! Is an application developed by Purdue University which approximates the resulting crater and after effects of an impact based on different selections of mass, velocity, impact angle, etc. Using the application, work with your team to produce a crater whose dimensions closely match those of the Barringer Crater. (Hint - You can reduce the number of variables by looking at what you know about the impact site and the impacting object.)