The EAST NICHOLAS RANGE An oddity. A presentation By David Leaman. SECRETS DEPEND ON ORIGINS. An understanding of just how and why the Nicholas Range is peculiar or special – an oddity – depends on knowing just how the range came to exist, and what forces and processes act upon it.
The EAST NICHOLAS RANGEAn oddity
Permian rocks, flat lying
Mathinna Beds: steeply dipping, folded
Unconformity: the mark of much erosion and lost time.
The typical style of the Triassic coal measures
Dolerite cap seen from the level of the Triassic lavas
The distinctive dolerite of the range cap peeps over the foothills.
Another remnant of a lost plateau: St Patricks Head
The dolerite-derived debris (talus and scree) which drapes most slopes
Geological map of eastern Nicholas Range north of St Marys
Sections across the range:
note the unconformity, lava zone, coals and surface drape deposits.
Westerly systems have predominated, along with occasional Southern Ocean depressions, and Bass Strait passage depressions: much as now.
Note the absence of
a seasonal pattern
with a winter surge
in the Break O’Day
Diagram showing water circulation in the Nicholas Range
Land stability depends on water transfer and volumes and may involve
surface materials or bedrock.
Diagram stresses flow controlled by coal measures and basalt, and major fractures
or failure surfaces. Cross-unit flow is minimal.