Sunday, 2 December 2007
Although the GPS tracker is giving Hatherleigh as the end of the road for today, the web diary suggests Mark cycled a few kms further and ended the day at Millicent.....Since yesterday, I've been doing a bit of research into the formation of the sand 'spit' in the Coorong. It seems that the entire area is indeed a relict dune system dating back some 120,000 years. The oldest dunes form parallel ridges in the landscape and are still visible from the air to the east of the Princes Highway along which Mark is now cycling towards Melbourne. Between 6,000 and 20,000 years ago sea levels rose (the result of ice melt at the end of the last Ice Age) and inundated this ancient dune system. Sea water flooded into the hollow behind the seaward dune ridge and created the Coorong. In the extreme south and east of the Coorong (shown here) the lagoon remains only as a series of shallow salt lakes between the road and the dunes.
A little further along the road today (sadly in an area of low res imagery)I spotted this road junction leading to 'Dalkeith' and I am reminded of how many place names in Australia are familiar. There is absolutely no doubt that this is a land which was predominantly settled by the British.
A bit of 'browsing' in the general vicinity of Mark's route today threw up this agricultural image ..
We have mentioned pivot irrigation before (as recently as yesterday) but it is probably worth considering why it is necessary in this part of Australia. The green spheres stand out against a background where there was little cultivation at the time the aerial view was taken. Yet there are clearly fields in the background and they must be in cultivation at some point in the year.
The explanation is related to the Mediterranean climate which this area enjoys. Here is the climate graph for Adelaide (from a German website ). Precipitation is shown by bars and read from the left hand scale and temperature is shown by the line and read from the right hand scale. Months are along the bottom but go from July to June. This is a climate of hot, dry summers and mild, moist 'winters'. There will just be enough precipitaion for cultivation to be possible during the cooler months but the summer drought will prevent cultivation except where irrigation as above is possible.
I am feeling that today's posting is developing into a miscellany but once you start exploring an area, it's amazing how many threads it throws up... for example, although Mark is cycling several kms inland, the whole area of South Australia through which he is travelling towards the border of Victoria is called 'The Limestone Coast' . The name derives from the thick deposits of limestone which underlie the region and give rise to some pretty spectacular caves in the area. There is plenty to read here about visiting the area.
Finally, if you look back at the first map on today's posting, you will see that there is a very different land use just east of Millicent where Mark has ended the day. Closer inspection reveals commercial forest ..... ... and a bit of 'exploration' on Google Earth near to Millicent produced this... It is a huge pulp mill, owned by Kimberly Clark, producing pulp which, amongst other things, ends up in nappies. The pulp is produced from radiata pines which are locally grown and produce a pulp called 'Southern Pine Fluff Pulp'. The large ponds in the distance of the aerial view are for treating the effluent from the pulping process and they, along with other processes, are well described in the environmental standards section of the website.
I have to say that a pulp mill using locally sourced timber was the last thing I expected to find in South Australia but as I've said before, I'm learning something new every day on this journey.