Journal of the Royal Society of Western Australia, 87(3), September 2004 
Figure 10. Cascade of rock basins draining north (away from the camera) and located between a rampart buttressed by quartz (left) and 
slope of the hill (right). Low rise or platform, devoid of trees, in middle distance (see separate outcrop NW of hill on Fig 1). 
Figure 11. Weathered sheet remnant on Level II in the southwestern sector of The Humps. Polygonal cracking has been exploited and 
plates weathered away, leaving some polygonal remnants upstanding as 'mogotes'. 
Impacts of seismic events 
Though seismically stable by comparison with some 
parts of the world, the southwest of Western Australia is 
one of three relatively active sectors within the continent 
(e.g. Gordon & Lewis 1980, pp. 209-214). The formation 
of new fault scarps is reported from several sites from Mt 
Narryer in the northwest to Lort River in the southeast. 
The impacts of the Meckering earthquake of October 1968 
are well known, evidence of active warping (as opposed 
to faulting has been detected in the Northam area and 
two periods of activity on the Hyden Fault have been 
identified (Thom 1972; Williams 1979; Gordon & Lewis 
1980; Wellman & Tracy 1987; Twidale & Bourne 2003; 
Crone et ah 2003). Thus, it is not surprising that, like 
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