My exploration and documentation of craters (presently only on this planet).
Holleford RASC GA Tour
HOLLEFORD IMPACT STRUCTURE
AGE(ma): 550 ±100 a
Diameter: 2.35 km
Location: Ontario, Canada N 44° 28′ W 76° 38′
Shock Metamorphism: PDF in quartz grains (Robertson, Bunch, 1968)
a Dating Method: Geological – estimated to be in the latest Proterozoic or earliest Paleozoic times (Grieve 2006).
The Holleford Impact Structure is located 27 kilometres north of Kingston and 132 kilometres south-west of Ottawa in southern Ontario. Confirmation of the structure as an impact site dates only to the mid-1950’s. Several farms had been maintained at the site and the in the recent past aircraft have been flying overhead without anyone noticing that this may be an “unusual” structure. This is not surprising as the depth of the structure is only ~ 30 m (Beals 1960).
A systematic study of 200,000 aerial photographs of areas of the Canadian Shield was commenced in the early 1950’s when the Pingualuit Crater (formerly Chubb and then New Quebec) and the Brent Crater were confirmed as impact structures. As a result, Holleford was identified as a “structure of interest”. Over the years since that search, scientists have pieced together much of the Holleford Structure’s geological history (UNB 2003)