Wits team shows how lightning shapes mountains
10 January 2014
Scientists at Wits University in Johannesburg have made a "shocking" discovery –
lightning rather than ice or heat is the main force shattering rocks on Drakensberg
summits.
National Geographic reports on research published in the journal
Geomorphology on 1 January 2014. The evidence gathered by
geomorphologist Stefan Grab and geologist Jasper Knight has apparently changed
their own conventional notions about the forces that shape mountain peaks.
For their research, the pair surveyed almost half a kilometre of the Drakensberg in
Lesotho, where they found 90 sites where lightning strikes had blasted apart the
basalt rock face, the website reports.
While frost alters the shape of rocks over thousands of years, lightning - at
temperatures of up to almost 30 000°C - can shatter rocks milliseconds, the
researchers say.
Lightning "basically causes a bomb to explode on the rock surface", Knight told
National Geographic.
The fact that a lightning strike will partially melt basalt in an instant meant the
researchers were able to develop a diagnostic "tool kit" to distinguish the sites of
lightning strikes from other rock fragments affected by heat or ice.
Lightning is "part of the much bigger jigsaw," a puzzle piece that had been "passed
over by geoscientists for decades", Grab is quoted as saying.
The two researchers told National Geographic that further exploration would reveal
other examples of mountain ranges shaped in large part by lightning - especially in
warmer regions of Australia, Africa, and Asia that were mostly passed over by the Ice
Age.
SAinfo
reporter and National Geographic
The uKhahlamba Drakensberg Park has outstanding natural beauty, Africa's highest mountain range south of the Kilimanjaro, and the largest series of rock art paintings in Africa (Photo copyright Walter Knirr, South African Tourism)