20. Haughton, Canada (Geologic Map on Air Photomosaic)
This image was generated by fusing two co-registered datasets, a lithological map and a digital mosaic of four air photographs. This produces an image that shows all the original information of the black-and-white photomosaic but now colored according to the lithological data. Beyond the central region still covered by impact breccia, arcuate concentric fault-bounded valleys clearly define the crater's outer flanks, from which any ejected breccias deposited have been stripped by erosional processes. In the central part of the crater, isolated exposures of deep target rocks uplifted during the late stages of the impact process protrude through the thin cover of impact breccia. The deepest unit shown is the Eleanor River Formation (shown in green); away from the crater this unit is located at a depth of ~1800 meters. Geological information indicates that these outcrops stood as isolated topographic highs on the original crater floor as a true central peak or possibly even a peak ring, as discussed in the next slide. Farther out to the east and north, shallower uplifted units are now exposed, but were most likely covered by impact breccias immediately after the crater formed. The silty deposits of the Haughton Formation document that a lake formed within the crater immediately after its formation; the deposits filling this lake indicate that this region was warm and wet 20 million years ago, and that it supported a number of animal species, including rhinoceros and rabbits.
Image courtesy of V. L. Sharpton.