Wednesday, February 27, 2008

A new way to enjoy photographs

Anybody who takes more than ten photos per year (and everybody has at least a point-and-shoot camera these days) needs a good online photo sharing service. I have been a diehard fan of Smugmug for several years now. I love the elegant, somewhat Apple-like interface, the slick animations, the ability to easily organize and tag photos, the fact that pictures can be displayed at seven different sizes, that it is easy and fast to order high-quality prints, not to mention the significant integration with Google Maps and Google Earth. While I have realized that Flickr seems better equipped for more 'Web 2.0' interactivity (maybe largely due to the sheer number of users and photographs), and that there are far more photographs of turbidites on Flickr than Smugmug , I find the Flickr user interface confusing and its design inferior to that of Smugmug, with a lack of style that does not do justice to the zillions of great photos that are out there on the servers.

Having said that, I have recently started to use and appreciate Flickr a lot more. The reason: the updated Apple TV can stream photos directly from Flickr. Television sets with high-definition screens might be a bit ahead of the time due to the limited number of easily (and cheaply) available HD TV programming and movies, but they are perfect for displaying even relatively low-resolution photographs in brilliant colors and surprising clarity. After all, the best HDTVs have a pixel count of 1080 x 1920, and you get more than two megapixels with most digital cameras. Sitting down with a glass of wine and discovering good photographs on a big screen while listening to music is my favorite new pastime and I think it is a lot more enjoyable than browsing photos on much smaller computer screens that usually have a lot of clutter in addition to the photograph.

Now, if Apple was smart and kind enough to put Smugmug on Apple TV as well...

Saturday, February 23, 2008

Dish structures

Dish structures are sedimentary structures found in thick sand (or sandstone) that have concave-up, bowl-like shapes. They form when water is trying to escape from rapidly deposited sand but encounters horizontal barriers of somewhat lower permeability (usually zones with smaller grain size and/or dispersed mud). These force the water to flow laterally until it finds a place where it can go upward again. In the meantime, the subtle permeability differences get enhanced as muddy particles are washed away from the cleaner parts of the sand and concentrated in zones of lower permeability. The sides of these lower perm zones bend upward as the water finds its way up. Eventually pillar structures, vertical zones of cleaner sands can form on the sides of the dishes.

Initially dish structures were thought to be related to the (still somewhat fuzzy) mechanics of sediment transport and deposition in high-concentration gravity flows. However, clear examples that showed primary sedimentary structures (like cross lamination) being cross cut by dish structures proved that the latter are secondary structures, formed soon after deposition.

Probably because rapid deposition of sand is a requirement for the formation of dishes, these sedimentary structures are largely restricted to deep-water sands. Here are some examples that I think are blogworthy:

This one is from the northern California coast. Note the pillar structures between the dishes. [Apologies for the lack of scale - I think this bed is about 4 feet thick].

This is a zoom-in of dish structures in the Cerro Toro Formation of Southern Chile. Lighter-colored areas probably contain less mud than the darker zones.

No scale on this one either (there was no way I could climb up there), but trust me, these are probably among the largest dish structures in the known universe. They were photographed in northern Peru, near the town of Talara.

And to prove that they are really big, here is a photo that gives an idea of their scale:

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