Clay day!

Months ago, on a field trip, I was discussing my research with one of the members of my committee. I mentioned I was thinking about incorporating some modeling into my work, and while I was thinking computers, he suggested clay.  Nothing fancy, just using clay to deform some layers in a "back of the envelope" kind of way.  I spent a lot of time thinking about it, especially as I've agonized over interpreting faults in my 2D seismic data. Would slicing a 3D model open at different angles help me figure out what things might look like in 2D?

Fast forward to this month, and I'm trying to get a preliminary version of a fault map done for my study area to go with a draft of my research proposal for my committee. I'm having a hard time committing to my interpretations (something I've struggled with since undergrad, when I always said I needed more data for my subsurface geology labs).  

Seismic is an amazing tool, but I love being a geologist because it is so tactile. I decided I needed clay.  It arrived today.  This just might replace colouring as one of my favourite things about being a geologist (although nothing will ever replace being in the field at the very top of the list).

A new package of modeling clay!

I don't think I actually expected to solve my interpretation problems the first time I played with my clay, but after spending a bit of time working with it, I wasn't sure I was going to solve any problems with it.


Using 2D imaging to look at a 3D world is a problem in geology, not only when you're looking at seismic, but often when you're looking at the face of an outcrop. It's easy to misunderstand what you're seeing because you're not seeing the whole picture. Something that looks like this from one angle:

One side of a smooshed ball of clay

 looks like this from another angle:

The other side of the same smooshed ball of clay.

The African Great Lakes

If you are from Canada or the United States, when you hear "Great Lakes,"  you probably think of these five bodies of water:

The Great Lakes of North America

North America is not the only continent to have Great Lakes; Africa has its own great lakes. Exactly which of the East African Lakes are considered Great Lakes is a bit subjective, but I've labeled the most commonly referred to ones on the zoomed in map below. The African Great Lakes, as well as the smaller lakes found in East Africa are part of the East African Rift System, which will I'll write about in later posts.

The African Great Lakes

The Great Lakes

Some facts about the African Great Lakes:

• Lake Victoria is the second largest continental lake in the world by surface area (after Lake Superior)
• Lake Tanganyika is the second deepest continental lake in the world (after Lake Baikal)
• Lake Tanganyika is the second largest continental lake by water volume in the world (after Lake Baikal)
• Lake Malawi has more species of fish than any other freshwater lake
• Lake Tanganyika is the longest lake in the world

All maps created using http://www.geomapapp.org/

The beginning

There was a moment, in Kenya, when I looked around at where I was and thought, "this is it. This is what the hard work of the last two years has been for."

I just spent five weeks in Kenya as part of the science crew for HSPDP - the Hominid Sites and Paleolakes Drilling Project. Africa changed me, as it does for so many people, in ways that I probably won't discuss publicly. It also rejuvenated my passion for the research I am doing right now. I'm still organizing my thoughts and photos from the whole thing, but there will be some posts to come.

In the meantime, I've written a post about the one-day safari I went on in Nairobi National Park over at my travelblog.  Check it out here (safari blog) for an account of our adventures - and there were several - and photos of African wildlife.

My last sunset in Turkana

En route to my fifth continent

I'm at Chicago O'Hare right now, on a layover between Syracuse and London. Once I get to London I have another flight to Nairobi, Kenya.

I'm joining the science crew of HSPDP, the Hominid Sites and Paleolake Drilling Project. They are making good progress at the first Kenyan location, at Tugen,Hills near Lake Baringo. In fact things are going so well they'll be done before I get there.

I do get to head up to West Turkana to the second location. We'll be working out of a camp and it's so remote there is no phone or Internet.

I'll have lots of new things to blog about when I get back on July 16 (as well as tackling the backlog of posts I have to catch up on from the last year) but in the meantime I encourage you to search for the HSPDP facebook page. You don't need to have a Facebook account to see it, and that's where the best updates and photos are being posted.

Dunes in Death Valley

On our first night in Death Valley, we camped at Stovepipe Wells. It's a wide open campground, one that I wouldn't want to be in during the heat of summer, but it was a perfect starting point for our first day's itinerary.

Early morning at Stovepipe Wells

As you can see from the photo above, it's a sandy part of Death Valley. In fact, just a short drive from the campground (~ 2 miles) are the Mesquite Flat Sand Dunes, so called because of the mesquite trees among the dunes.

The dunes cover a large area, although the highest one is only 100 feet
(http://www.nps.gov/deva/naturescience/sand-dunes.htm)

Mesquite

Sand dunes are formed by wind-blown sand. When the sand supply, wind direction, and velocity change, so does the type of sand dune that forms:

• Transverse: constant wind direction and large sand supply
• Barchan (crescent): constant wind direction but limited sand supply
• Linear (seif): converging winds and limited sand supply
• Star: variable wind direction

You can tell which way the prevailing winds blow from the shape of the dunes.

The wind blows the sand up the long windward slope and down the steep leeward slope.

This photo is of the steep (leeward) side of the dunes.
I think the stripe of shadow going down the dune on the right side of the picture is where we went dune running.

Assuming that the shadows are on the leeward side, the prevailing winds blow in the direction of the arrows.
These are mainly linear dunes, but the smallest arrow is pointing to a set of barchan dunes.

Google Earth Image of the sand dunes near Stovepipe Wells.
The red star is the approximate location of the Mesquite Flat Sand Dunes carpark.
The black square shows where the map above is located.
The blue lines outline different types of dunes.
The yellow circle shows a star dune.

Walking across sand dunes is difficult, and climbing up them is grinding, but it is worth it to run down the side of a dune and feel a little bit like you are flying... Those of us that chose to do the dune run left our bags and cameras with the spectators in our group. On the way back, I saw a ripple mark in the sand that wasn't made by the wind, it was a snake track. It would turn out to be the closest we came to seeing a snake on our southwest trip (although a couple of us were on a different field trip to Massachusetts in April and we saw a ribbon snake on that trip). Fortunately, one of my friends had a camera, and he took a photo of the snake track.

Snake track. Photo courtesy of Callum McMillan.

The sand dunes are surrounded by mountains.

In my last post  I showed some pictures of sand dunes preserved in the rocks in Australia. Here's one of those photos again, this time annotated to show the wind direction when the dunes formed. 

At least two different sets of dunes preserved in the Mereenie Sandstone in Australia.
The arrows show the paleowind direction.

If you want to know more about how sand dunes form, I encourage you to look at Chapter 16 of Earths Dynamic Systems, found online here.

Ancient Australian Dunes

Lens cap (bottom, left of center) for scale.

Lens cap (middle, left of center) for scale

I'm working on my next Death Valley post, but in the meantime, here are two quick photos of some beautiful cross-bedding in the Mereenie Sandstone at Kings Canyon, Australia.  360 Ma, there was an inland dune field here. That's right, these were sand dunes! Unlike the coastal dunes on Lake Ontario that are made up of beach sand, these ancient Australian dunes are thought to have formed in a desert. The Australian deserts today have dunes too.


Source: Thompson, R., 1995, A guide to the geology and landforms of Central Australia: Northern Territory Geological Survey, Alice Springs, Northern Territory, Australia.

Death Valley: Dante's View

I don't think I was prepared for how amazing Death Valley would be. I'm not sure what I expected, but there was a little bit of everything there. The SU Geology Club spent a couple of days there on our spring break field trip, and it was just enough to get a thirst for more. Death Valley's dramatic landscapes are the result of recent rifting and extension but the rocks in the basin record a longer history of the western margin of North America (Miller, 2005).

Death Valley is approximately 200 km long and varies from 8-25 km in width, with 1-3 km deep sediments filling the steeply walled valley (Hussein et al, 2011).

Dante's View overlooks Death Valley from an elevation of 5474 feet (1669 m). If you can get up before dawn to get there, you will be rewarded by a gorgeous sunrise behind the peaks to the east and you'll see the light creep down into the valley. Some of my sunrise photos are at the end of this post. 

Dante's View is on the Black Mountains which have been uplifted along the still active Black Mountains fault zone (Miller, 2005). Across the valley are the Panamint Mountains. From Telescope Peak (the highest point in Death Valley National Park) to Badwater Basin (the lowest point in North America), there is an elevation difference of 11,331 feet (3455 m).

Telescope Peak.

~11,000 feet (3000 m) of elevation change

Death Valley is a classic example of Basin and Range topography: uplift of mountains along parallel normal faults leaves linear valleys between the mountain ranges (Hill and Troxel, 1966).  It is also a great place to see alluvial fans. It's hard to get a sense of how big alluvial fans are unless you can see just how thick they are:

Daylight has almost reached the tops of the alluvial fans.
Yes, they really do go nearly halfway up the mountains!

In the early morning light, shadows mark the canyons that feed the alluvial fans.
The shadow of the Black Mountains still covers most of the alluvial fan and the valley floor.

Many channels can be seen flowing down the fans

Panamint Mountains and the shadow of the Black Mountains in Death Valley.

References Cited:

Hill, M., and Troxel, B., 1966, Tectonics of Death Valley region, California: Geological Society of

America, v. 77, p. 435–438.

Hussein, M., Serpa, L., Valasco, A., and Doser, D., 2011, Role of sedimentation in continental rifting

from comparing two narrow rift valleys the Salton Trough and Death Valley-California: Natural Science, v. 03, no. 11, p. 927–935.

Miller, M., 2005, Geological landscapes of the Death Valley region: Earth-Science Reviews, v. 73, no.

1-4, p. 17–30.