Thursday, April 25, 2019

Geosonnet 53



An opal is the desert’s hidden gem
Precipitating from a torrid brine
Geologists from arid zones condemn
Ideas that ice, not heat, can redefine.
The glacial polish, hiding in plain sight
Amorphous silica precipitate
Dissolved from glacial floured andesite
It coats the scoured rock with silicate.
Will Coober Pedy yield to Mawson Base?
Should new chums and their ratters venture south?
Probably not; a glaze on orthoclase
Will not put food in hungry digger’s mouth.
   For chemical erosion makes a rind
   So thin that only TEM can find




Other geosonnets: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

Wednesday, April 17, 2019

Geosonnet 52



Peridotite, without the peridot
A paradox, clinopyroxenite
What metasomatized this mantle plot
Reacting mantle min’rals out of sight?
A garnet, like an elephant, forgets
No detail of its formative hot years
Included in its structure, tiny bits
Of felsic melt, the mantle’s frozen tears
A crustal rock’s subducted ‘till it melts
The rock’s identity is not air tight
Melanosome in metamorphic belts?
Or metasomatized old hartzburgite?
The isotopes of osmium declare
They’d solve this if they weren’t so very rare



Other geosonnets: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52




Monday, April 08, 2019

Preserved Lemmings

I don't know what the elimination of G+ is going to do to this lounge, but if there is an interruption, please note that several years ago, the National Library of Australia decided this blog was worth archiving. The government archive version is here:
http://nla.gov.au/nla.arc-126431
So now lemmings can lounge on both the north AND south sides of Lake Burley Griffin.

Thursday, March 21, 2019

Shameless self-promotion and self-organizing

I keep losing the link to the Supplementary Information from my Geology paper (summarized as Geosonnet 42), so I'm posting the direct link here, where I hopefully won't lose it.
http://www.geosociety.org/datarepository/2016/2016176.pdf
And before you tell me a better way to keep track of things in the digital age, GET OFF MY LAWN!

Monday, February 18, 2019

Geosonnet 51

When oxygen and oceans mixed worldwide

Out dropped the world’s first heavy metal band
With silica and iron side by side
This rocking BIF precipitate was grand.
But modern industry required more
Than hematite with intermingled chert
The silica component they abhor
Must be expunged by fluids which convert
The BIF into a high grade iron mine
A cooling basal fluid can’t displace
As much quartz gangue as pulsing solo brine
With carbonate fade in- not acid- bass.
When silica got kicked out of the band
The iron oxide satisfied demand.



Other geosonnets: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52

Saturday, February 09, 2019

Sierra Sequoias from space

I wrote last year about the big trees of the Sierra Nevada mountains in California. One if the things that interested me was the ability of the Sequoia and the Sugar Pine to grow side-by-side, despite having very similar survival strategies- namely grow taller than everything else and live long enough for fire to clear our the shade tolerant trees so that your seeds can germinate.

Of course, as anyone who spends time on the forest knows, despite these trees having similar niches, they look quite different. The both have large trunks often bare of branches for the first 100 feet, but their vegetation has different forms. The Sugar Pine has very long, straight lateral branches, like the spars of a ship, while the sequoia crowns are more rounded. And because these trees are very large, it turns out that you can easily distinguish them in Google Earth. Here is a screenshot of the same grove I wrote about last year:

You can clearly see the long lateral branches on the pines (which also have somewhat bluer foliage). The larger, yellower trees with very wide trunks and rounded foliage are the sequoias.

Unfortunately, the sugar pine is in decline in many areas of its range, Here is a picture of dying trees in the national forest just south of the park:
The most obvious thing here is that the Sugar Pines are mostly dead. But there are other differences. Unlike in the National Park, here you cannot see the ground- the trees are growing too close together. One critique of the Forest Service is that it as lagged behind the Park Service in the use of controlled burns and recurrent fires. While I don't have the fire history of this exact area, the much thicker understory could be the result of decades of fire suppression. And if those trees are sucking up all the water, perhaps that has stressed the pines.

Sunday, January 20, 2019

Book Review: William Shakespeare’s Star Wars


By Ian Doescher
This is a stage adaptation of the plot of the original Star Wars movie, written in Iambic pentameter. It’s not done too badly, with lots of actual famous Shakespeare lines sprinkled throughout. And it is a clever idea. However, the joke gets old quickly; I gave up before they even got to Tatooine.