Old Trails: Hiking Up The Tufa

Hotel-Sized Tuffa, Namibia

We pulled up to the farmyard and stopped at the fence causing the cloud of dust to catch up and swirl past the gate towards the house. We got out, research permit from the Namibian Geologic Survey in hand, walked to the fence and waited. After a couple minutes passed a white farmer with a shaven head and sporty sunglasses stepped out of the house and approached us. We explained we were geologists from McGill University in Canada and asked permission to hike to the tufa, pointing across the graded dirt road which acted as Namibia’s highway system. I don’t remember the farmer saying much, if anything. He nodded, and went back into the farm house.

Recently, I started the gargantuan task of reorganizing and backing up all of my photos. This led me to dig through some archives and to revisit photos that I have not shared with many people. When we visited this tufa I had not yet been introduced to the sport of rock climbing. Looking at these tufa photos now, I see lines, unclimbed, begging for someone to clean and send. We didn’t climb the tufa, we hiked around. Here are some photos from that hike.

Hking through the grass to the tuffa.

After stopping at the farmhouse we pulled off the highway. Christie, my advisor, insisted that she needed a nap and waved us towards the tufffa while reclining the driver’s seat. We crossed the wire fence and made our way into the waist high grass. That two hundred meter walk through the grass was one of the most stressful moments of my life. There are snakes in Namibia. Pofadders, Cape Cobra, Black Cobra, and Black Mambas frequent my field area. At least when we’re out on the hill slopes there is less grass and we can see where we are stepping. Tanya, Ben, and I were all nervous and let out big sighs when we exited the high grass.

Namibian waterfall!

The tufa was gorgeous, huge, and loomed overhead. Yellow-green slim covered wet rock where water dripped down. A little waterfall ran sprinkled and slid over the tufa, collected in a pond, and trickled away in a stream that disappeared into the desert.


We stepped to hike around and up the tufa where we got a special treat. Diamictite. B-E-A-utifully deformed diamictite. Diamictite is a rock that is a mix of rock clasts in a muddy matrix. These diamictites had since been deformed, shown by the elongate stretched, clasts.


We turned and continued upward, following black plastic pipes that ran from some unseen spring above us.

Hiking up.

The hiking was steep, but not strenuous. Before we knew it the incline shoaled and we began topping out over the tufa. The top was like a geologist’s dream. A folded cap-carbonate could be seen on the mountainside framing the valley before us.


We paused to look back towards the car, where our professor lazily dosed, probably dreaming of pseudotachylyte and fault gouge.


Our tufa foray wasn’t over yet, we followed the stream that had built this tufa up. It takes time to build a deposit like this. Calcium carbonate precipitates from the water. We saw breccias too. Head-sized, angular clasts of limestone that had once been shot down the stream, maybe during a rainstorm, only to now be cemented in the tufa.


Outside of the stream we spotted more folded limestone.


The breccias become the tuffa, cemented in the streambed. Other rocks, with the power of water pushing them forward, polish and erode the surface of the cement. Ponds between trickling streams form. Desert life revolves around water. Where it is abundant so is life and green.


Big tadpoles swam in the ponds we passed. I saw something unexpected in the desert: a bullfrog, quietly crouched near submerged rocks.

Namibian bullfrog

What other treasures would we find hidden in the hills? The only thing to do was follow the water.


Finally we reached a point where the stream cut into rocks. To continue following it we had to leave it for higher ground. Unfortunately we hadn’t come prepared for canyoneering on this hike. Ahead and below us we caught glimpses of caves and pools hidden in tufa slot canyons.

DSC_1821 DSC_1834

We ended the hike at this crystal blue pool. The water looked amazing, but strange yellow algae covered the surface of every rock below the water. Swarms of black water bugs oscillated in the turquoises liquid. We tossed a small rock in and watched as they scattered to the edges of the pool, then swam back into pulsing mosh pit.


The pools were gorgeous, but so were the rocks. I’ve always been fascinated by structures in rocks, whether tectonic or diagenetic in origin. The limestone structures influenced their surficial weathering and thus the growth of lichen.

Limestone structures


Time to head back. Christie had sent us up here to check out the tuffa and examine the diamictite, but we’d all become mesmerized by the pools and the life around them.





I don’t remember which way we came down from the tufa. Nor do I recall if we trod through the waist-high grass or followed the stream to the road. I think at that point I was overwhelmed by the beauty of a little desert treasure.



Friday Rocks #39: Soft Sediment Deformation and Flame Structures

Soft sediment deformation at Point Lobos, California
Soft sediment deformation at Point Lobos, California

This weeks photo comes from a spectacular outcrop at Point Lobos, California. If you are there, try to time it with low tide, or you’ll miss this.

Soft sediment deformation occurs in unlithified sediments. Sometimes a trigger such as rapid loading by a mass wasting event or an earthquake is necessary to cause the deformation.


Flame structures (middle right in the photo) form when the overlying sediment (orange) is denser than the underlying sediment (black). This causes the overlying sediment to sink down into the low sediment, which pushes the lower sediment up. The structures formed resemble flames, hence the name.

Also in the photo (near the pointing finger) is a more competent sediment that was normal faulted as the unlithified sediment below it deformed. What other structures do you see in the photo?

Here’s another shot of the flame structures.

Point Lobos Flame Structures
Point Lobos Flame Structures

On Climate Change, Glaciers, and the Rock Record

Paul Hoffman (Department of Earth and Planetary Sciences, Harvard University) is one of the best orators I’ve seen. When I saw this talk by Paul Hoffman at McGill last year I was completely blown away. Not by the science, but by his skill as a story-teller. Paul Hoffman didn’t just tell us why we know the climate is changing, he told us the history of how we got to where we are today in our understanding of climate and Earth’s history. He started with the history of our understanding of glaciers, through the development of the “Snowball Earth” hypothesis, and the importance of the geologic record in climate science.

The talk is about an hour long and well worth it. Find it at the link below.

Paul Hoffman at McGill Redpath Freaky Friday Talk

Wikipedia Articles of Geology Enhancement Project

Last year the students in the Tectonics course I TAed were assigned the task of repairing geology and tectonics related Wikipedia articles. Students had to select a Wikipedia article with sparse or incorrect information, research the topic, and submit an improved version of the article for review. The TA then reviewed the new article version and only after the students submitted revisions was the article approved for publication on Wikipedia. Here are the issues students tackled last year:

Students are responsible for seeking out and selecting topics to research. We encourage them to focus on process articles, but articles about important locations are also fair game, especially if they exemplify a specific tectonic process. This year we will be sending out the Wikipedia Tectonic Stubs list to the students as a springboard for finding their topic. However, I wanted to reach out to the geo-blago and twitter spheres for topic ideas. 
So I ask you all, what geology and tectonics articles on Wikipedia are in need of attention? Respond in the comments section below, on twitter (@tsherryUSA), or in your own blog post (please send me the link!).

Something may be wrong with the comments on this blog. Feel free to send me a message with your comment and I’ll add it to the post.
Comment from Matt Hall of AgileGeoscience:

I finally got around to reading this after a lot of travel. It’s terrific — I’m so glad to read about the exercise and its outcomes, so thanks for reporting.

While I definitely don’t want to discourage people from building up their own ‘to do’ lists in Wikipedia, I did want to point to one other resource for finding articles that need work (you already mentioned the stubs lists at http://en.wikipedia.org/wiki/Category:Geology_stubs.
WikiProjects try to consolidate efforts on certain topics. WikiProject Geology maintains a list (http://en.wikipedia.org/wiki/Wikipedia:WikiProject_Geology/Assessment) of high priority articles that need work (it takes a minute to parse the colourful table), and also a To Do list of tasks (https://en.wikipedia.org/wiki/Wikipedia:WikiProject_Geology/Tasks). These can be good places to look for inspiration.
Cheers! Matt


Thanks for the links, Matt! I’ve passed them on to our students.

Drilling Deep for Earthquakes


This video was posted on the California Academy of Sciences website. Here Harold Tobin explains the goals of the NanTroSEIZE drilling project and how it ties into the larger picture of earthquake hazard assessment. This ship was also used during the JFAST project to drill the Tohuku earthquake fault. I’ve posted about the JFAST project before and here or learn more from their official page.