As
we crossed the border into Northern Territory we were overcome by how huge this
country is! We drove for days along the same road and saw nothing for hours at
a time. The landscape subtly changed into the dry dessert of Central Australia.
Changing
our clocks back, we arrived at Barkley Homestead, exhausted and hungry. A quick
dip in the pool was very refreshing and a trip to the pub filled our bellies. A
load of laundry the next morning (which dried in about 30 minutes!) and we were
ready to hit the road again.
The
road from Barkley Homestead to Three Ways, was the longest and straightest we
had ever driven on. We were surprised by the lack of wildlife (both living and
dead) and figured it was too dry and hot out here for even them.
Along the way we saw giant plumes of smoke on the horizon. As we got closer, we realised that the locals were undertaking controlled burning of the undergrowth. Driving past, we could feel the heat of the fires through our car windows, and chills went up my spine at the thought of being trapped out here in a bushfire.
The second phase of the formation of the Marbles started when the blocks were exposed to water. The surface of the blocks began to decay under the influence of the water, and a layer of loose material surrounded the individual blocks. When they came to the surface completely, this layer was flushed away by water and blown away by wind.
The rounding of the granite blocks is a result of both chemical and mechanical weathering. Firstly, exfoliation plays a part. Chemical processes cause the surface of the blocks to expand and/or shrink. Thin layers of rock come off the boulder. This rounds the granite block, because the chemical processes have more effect on areas with edges. These processes cause the rock to look like it is made of layers like an onion. In effect, only the outer few centimetres are affected by chemical weathering. This process is called spheroidal weathering. Secondly, the boulders are suffering from solarisation. Because the temperature differences between day and night are so great, the rocks expand and shrink a little bit every 24 hours. This causes some rocks to crack, sometimes even splitting them in half.
Another
long drive today and we will arrive in Alice Springs where we will spend the
next few months. I don't know what to expect from Alice Springs as I have heard
many different stories from lots of people. We have got an interview with the
Steiner School to see if they will accept the boys for next term, which will
give me a well-deserved break from playing teacher-mum, and give me some time
to play one-on-one with Zaccy.