Geological and Social History of our Alum Cliffs

Patricia Roberts-Thompson (http://taroona.tas.au/assets/document/1354363720-a_walk_along_alum_cliffs.pdf) indicates that the first recorded reference to the Alum Cliffs was in 1847.  She explains that these rocks, Permian mudstone (250 million years old, contain iron pyrites and, as the rock weathers, the pyrite oxidises and produces sulphuric acid which reacts with the limey clay to produce alum. Roberts-Thompson could find no evidence that the alum has been extracted from our cliffs for commercial purposes.

Simon Stephen’s research (http://taroona.tas.au/assets/document/1352547986-geology_reduced.pdf) is in sync with that of Patricia Roberts-Thompson  when he says the mudstone on the Alum Cliffs contains much sulphur so that when struck a strong smell is emitted. “Much of the sulphur manifests itself as a white encrustation on thee sheltered areas of the cliffs. It has a distinct bitter taste…”  (Trust me – I won’t be taking a bite or licking it). Stephen’s article is exceptionally interesting not the least because it pin points a geological fault line which is near Crayfish Point (where I have already walked) and which extends out through the end of Hinsby Beach and then under the water along the Alum Cliffs.  I don’t know if any seismological activity has occurred in my life time there nor whether any is expected. I’d rather nothing happened during my forthcoming Stage 12 walk along the Alum Cliffs.

The Kingborough Council distributes a brochure with the following information: “The route followed by today’s Alum Cliffs Track has long been a coastal path used by local people. In 1988 it was formally developed as part of Australia’s Bicentennial celebrations. In more recent years, Council has upgraded the southern section of the track, which climbs from Tyndall Beach through coastal blue gum forest with tall silver banksias. The track then winds up through silver peppermint bushland, dips into a glorious fern filled gully, before rising again onto headlands for commanding views over Storm Bay and the Derwent Estuary. A new start to the track without steps has now been constructed above Tyndall Beach to make the track accessible to more users. The Alum Cliffs are so named because alum – a compound used in dyeing, tanning and medicinal products – is found in the cliffs.”

It is a shame that all instructions to reach and walk the Alum Cliffs use Kingston Beach in the south as the base to walk north and then return. Websites provide information about multiple entrances along the route at Tyndall Rd, Harpers Rd, Taronga Rd.  Apparently a Metro bus stop is located 100m south of the intersection of Taronga Rd and Channel Highway. I wonder how many people have walked the Alum Cliffs Track from the northern end and, if not, like me would like to read advice about how to tackle the cliffs departing from Hinsby Beach.

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It may be that, on Stage 12, I will start out at the end of the Hinsby Beach and then be forced to retrace my steps, return to the Channel Highway and walk up the winding fairly narrow Highway with no pedestrian walkway until I reach the Brickfields Track. From http://www.greaterhobarttrails.com.au/track/brickfields-track I understand that “the Brickfields Track links between Taronga Rd (adjacent to the Channel Highway) in Bonnet Hill and links to the Alum Cliffs Track. The route of the Brickfields Track takes you through the historic remains of the brick-making area; part of the nearby and short lived 1840’s convict probation station. The track is a mix of narrow bush track and timber boardwalk with some steps along the route.”

2 thoughts on “Geological and Social History of our Alum Cliffs

    1. Tasmanian traveller Post author

      Thanks for your comment – I have lived a reasonable amount of my life in the Hobart area yet this walk along the Derwent is teaching me so many new things.I thought I knew so much and now of course I am faced with the fact I knew so little. So we are all learning together.

      Liked by 1 person

      Reply

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