Friday, 13 March 2015

Geology Field trip 1

It might be pedantic to say we didn't actually got to any fields today.  Possibly I could say we hung around (but that would be pendantic) various parts of the urban area looking at points of geological interest.

This started with a visit to the Federation Rocks, at the base (ie Lake Burley Griffin level) of the hill leading up to the National Arboretum.  This is the site of the future National Rock Garden.
Here is the array of current rocks.  There is one from each State or Territory and, according to the NRG site, they are placed in the order of the administration being officially designated.
I won't chew up your bandwidth with a snap of each of the rocks (especially since they are on the linked site) but did think this Harlequin Stone, gneiss from Wallaroo in South Australia was very attractive.
We then moved to the National Museum site to look at these limestone outcrops.  They were found by the the first European party in the area and formed an important resource since they could be processed into building products such as mortar.  They also gave rise to the name "Limestone Plains" for this part of the Monaro.
Also at the museum is this stromatolite from Shark Bay.  It was supposed to be inside the Mueum but was too heavy for the floor loading capacity of the building!
Next stop, for morning tea and a view, was the top of Mt Ainslie.  Unfortunately much of the macrogeology was concealed behind the smoke haze from various Habitat Reduction Burns being undertaken by the official sponsored fire-starters in the Region.
Then on to Geoscience Australia (GSA) where there are many resources available to those interested in geology.  They seem to be a bit more focused on resource exploitation than conservation (but then mining companies employ more geologists than do environmental groups).  This was the library.
This display is largely of crystals.  Very pretty but not in my opinion of great policy significance.
There were a couple of displays of great interest and significance.  The first is this real-time log of seismic events.  Click on the image to get an overall larger version: events more distant than 2 weeks appear as a pink dot (regardless of age) while the more recent one are sized according to magnitude.
This image shows a closer image of the area North of Australia. The deep orange circles are a couple of scale 4 events on the day we were there but the big yellow circle was scale 6 or 8 and occurred in the ocean South of Eastern Java in the past two weeks,  No coverage in the Australian media, so I presume it didn't cause a tsunami.  (In fact looking up the source of the data, IRIS - Incorporated Research Institutions for Seismology - it was a magnitude 7 and occurred on February 27. ) Note the almost continuous string of pink pearls across the middle of the image.
The other significant display related to the search for MH370 in which GSA is a major player.  They ran a video showing the result of scans by the sonar buoys which can be accessed from the GSA site.  Our guide commented that in places the results of this detailed scanning is changing the depth of seabed - previously measured by satellite imagery - by as much as 1.5 kilometres.

Out the front of the building were various rock displays - some of which are intended for NRG.  Possibly they are waiting for Tectonic shift to relocate them (Tectonic Movements - a great for a removalist business).

We then moved to the Mall in front of new Parliament House.  We found free 1 hour parking and I was pleased to see the Mad Monk's revenue raising scheme getting a two-fingered salute in this area.
We were there to look at this cutting which shows State Circle Sandstone (rippled layers on top) and City Hill shale below, with an unconformity between them.
All up a pretty good day.

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