Bruno Escarpment - The pale grey impact-produced breccias provided the heat source for the hydrothermal activity at Haughton.

It is now widely recognized that impact cratering is a ubiquitous process that affects all the terrestrial planets. The surface of the Moon, where other geological processes stopped billions of years ago, records this process clearly. On Earth, however, impact craters are continually erased by erosion, volcanism and tectonic activity. Thus, despite the fact that the Earth has been more heavily bombarded than the Moon, only about 160 terrestrial impact craters have been recognized to date, although several new structures are found each year. So why is the study of the impact hazard important? Well, we hope to learn what has impacted our planet in the past, and what effects these past impacts had on the structure of the Earth, its atmosphere, and its biosphere. Indeed, it is now accepted that a large impact event about 65 million years ago on Mexico’s Yucatan Peninsula redirected biological evolution on Earth. This event formed a crater approximately 180 km in diameter and resulted in the extinction of about 75% of life on Earth, including the Dinosaurs.

The beautiful Lake Sapphire stands out as a modern day oasis. Hydrothermal vents on the lake floor may have provided warm, wet sites for the re-establishment of life.

It is well known that hydrothermal systems will develop anywhere in the Earth’s crust where water coexists with a heat source. It may also be possible that hydrothermal systems provided a warm, wet site for the origin of life on Earth and other planets (e.g., Mars). During the last two summers in the Canadian Arctic, we have found evidence for the existence of a hydrothermal system formed by the interaction of hot, impact-generated rocks with groundwaters at the 24 km-diameter, 23 million year old Haughton impact structure on Devon Island. From comparisons with other impact craters and from certain thermal considerations, it may have taken as long as tens of thousands of years for the land to cool below 50°C following the impact. During this time, Haughton would have represented a warmer, wetter environmental niche relative to the surrounding devastated terrain. There is then, the possibility of life after death!