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The Mills College lobe

The big alluvial fan of old Pleistocene gravel making up Oakland’s most unusual topographic feature—the Fan—is cut by stream erosion into eight lobes, which I’ve numbered from west to east. Lobe 7 is entirely inside the grounds of Mills College, as shown here on the geologic map. Seminary Creek passes the west side and Lion […]

A Fleeting Spring in Yosemite: When Going Out Was Really Going In

“I only went out for a walk and finally concluded to stay out till sundown, for going out, I found, was really going in.” John MuirHas that kind of thing ever happened to you? We headed east yesterday afternoon on a short jaunt, ostensibly...Show More Summary

Morphology of a forced regression

'Forced regression' is an important concept in sequence stratigraphy - it occurs when relative sea level falls and the shoreline shifts in a seaward direction, regardless of how much sediment is delivered to the sea. This is in contrast...Show More Summary

Einstein, tea leaves, meandering rivers, and beer

If you make your tea the old-fashioned way, ending up with a few tea leaves at the bottom of the teacup, and you start stirring the tea, you would expect the leaves to move outward, due to the push of the centrifugal force. Instead the leaves follow a spiral trajectory toward the center the cup. Show More Summary

Deep-sea landscapes from the ice age

The upcoming edition of Accretionary Wedge is going to focus on geo-images. I was always fascinated by the beauty of landscapes and landforms, natural patterns and textures, as many of the posts on this blog can testify; that is one of the reasons why I became a geologist.However, this time I want to show a different kind of geo-image. Show More Summary

Garmin Forerunner 110 GPS watch - a review

A couple of years ago I decided to take running a bit more seriously and to try to keep track of when, how much, and how fast I run. As a dedicated Apple-afficionado and beginner runner, the obvious choice was the Nike+ sensor (which you place in the sole of your shoe), coupled with an iPod Nano. Show More Summary

Snorkeling and geology in Kealakekua Bay, Big Island, Hawaii

For a long time, I didn't think it was worth spending more than an hour on a beach, even the most beautiful ones, unless there were some nice cliffs nearby showing some interesting geology. My views in this regard have changed dramatically...Show More Summary

Texas wildflowers

The weather has been awesome around here lately (yes, in Houston!, the weather!, awesome!), and otherwise uninteresting roadside places are starting to be flooded with colors. Here are a few shots; more over at Smugmug.This one is actually...Show More Summary

Wave ripples on an eroding beach

I shot these photos in 2003, at Sea Rim State Park in east Texas, close to the border with Louisiana, a relatively remote and beautiful state park along the Gulf coast that suffered a lot of damage during both Hurricane Rita in 2005 and Hurricane Ike in 2008. Show More Summary

Lunar Crater volcanic field, Nevada

I was on my way to San Francisco / AGU last week when I saw these volcanoes and shot these pictures through the airplane window. It turns out that this is the Lunar Crater volcanic field in Nevada, named after the largest crater that is more than 1000 meters across and about 130 m deep. Show More Summary

The complexity of sinuous channel deposits in three dimensions

The beauty of the shapes and patterns created by meandering rivers has long attracted the attention of many geomorphologists, civil engineers, and sedimentologists. Unless they are fairly steep or have highly stable and unerodible banks, rivers do not like to follow a straight course and tend to develop a sinuous plan-view pattern. Show More Summary

Upcoming conference on seismic geomorphology

Ever since geoscientists and engineers started using seismic waves to figure out what lies under our feet, seismic reflection technology kept improving and today most oil-rich sedimentary basins have a wide coverage of high-quality three-dimensional datasets. Show More Summary

Evapor-art from the Permian Castile Formation, west Texas

The Late Permian Castile Formation is a ~500 m thick accumulation of evaporites in west Texas and south-eastern New Mexico. Its most striking feature is the vast number of alternating thin layers of lighter- and darker-colored deposits, layers that seem to be continuous across most of the Delaware Basin. Show More Summary

Two gigapans from Cliffs of Moher, Ireland

I shot these gigapans recently, while we were visiting some deep-water rocks in County Clare, Ireland (see more detail on these rocks and a few photos from the trip). One afternoon we took some time off from the turbidites to do a bit...Show More Summary

Three photos from Kauai

The rest are here. Colors in Alakai swamp Green turtle at Tunnels Beach Na Pali Coast

More reasons to conclude that coastal 'chevrons' are not related to mega-tsunamis

If there was any doubt left that coastal sand accumulations called 'chevrons' are not related to gigantic tsunamis (see previous thoughts on the subject here and here; Ole also has a recent blog post, and see a news release here), the May issue of Geology provides additional arguments to show that this is the case. Show More Summary

Hillslope diffusion

Modeling erosion and deposition of sediment using the diffusion equation is among the important subjects that are usually omitted from sedimentary geology textbooks. Part of the reason for this is that ‘conventional’ sedimentary geology...Show More Summary

Normal grading

In sedimentology, the word 'grading' has nothing to do with exams and assignments. Instead, it refers to a regularly decreasing or increasing grain size within one sedimentary layer. Because it is much more common than the other alternative, upward decreasing grain size is called 'normal grading'. Show More Summary

Description does not suffice for an explanation

On February 3, 1967, J. R. L. Allen gave the fifth "Geologists' Association Special Lecture", entitled "Some Recent Advances in the Physics of Sedimentation". This is from the introduction:"Two stages can generally be recognised in the historical growth of a reasonably advanced scientific discipline. Show More Summary

Three photos from Chilean Patagonia

I was lucky to attend a few days ago a field conference in southern Chile, looking at deep-water rocks in an area that includes Torres del Paine National Park. It was good to be back in this place of unbloggable beauty. The conference...Show More Summary

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