Geological specimen - Ventifact (wind- or ice-shaped) pebble

Historical information

Ventifacts are sand-blasted rocks that are typically faceted and often display parallel grooves carved by wind-blown sand. They are useful indicators of wind direction and strength in environments such as deserts, mountains, and coastal areas because they are usually not hidden by later sediment, soil or vegetation cover. In Antarctica ventifaction is strongly related to the composition or type of rock.

Ventifacts are important because they provide evidence for abraders such as sand, dust or snow and ice crystals, and offer a unique understanding of past wind processes that are effective in the reconstruction of past wind flow conditions and can provides clues to weather and climate changes in the past.

Interestingly ventifacts have also been found on the surface of Mars. They were a threat to the NASA rover due to the sharp angles of the facets, created by the Martian wind over the course of millions of years. These Martian ventifacts act like weathervanes for past wind and weather patterns on the red planet in a similar manner to those found on earth.

Significance

The Geological Survey of Victoria was instigated in response to the Victorian Gold Rush which began around 1851 in the Beechworth, Castlemaine, Daylesford, Bendigo and Ballarat areas. The survey was conducted by Alfred Richard Cecil Selwyn from his arrival in December 1852 until his resignation in 1869and during this time he trained many notable geologists, e.g. Aplin, Wilkinson, Daintree, who went on to other State survey senior positions. This specimen was among those donated to the Burke Museum in 1868.

Physical description

A hand-sized solid mineral specimen in shades of dark and light browns with light lines visible in all configurations and a groove on configuration 2.

Inscriptions & markings

light lines visible in all configurations and a groove on configuration 2

References

Back to top