Photo of the Week

Geology Photo of the Week #43

Matt Herod July 13, 2015

This weeks photo can be described by one word: mesmerizing.

Honestly, it’s hard to tell which part of this photo is better, the beautiful starry sky backdrop or the glow of Kilauea’s smoking crater. Combined, it’s just fantastic.

Kilauea is part of the Hawaiian Island volcanic chain which has been formed as the Pacific plate has moved across at hotspot. The volcano is about 300,000 to 600,000 years old.

Lava glow and space at the Kilauea volcano by Andreas Johnsson “Photo that unites the dynamic Earth and its place in Space. The photo was taken during the NASA-Nordic Winter School in Astrobiology in Hawai’i.”

Geology Photo of the Week #42

Matt Herod July 6, 2015

This week’s photo is a beautiful example of geochemistry in action. Briefly, travertine, which is composed of CaCO3 is often precipitated at hot springs as they emerge from the ground forming these gorgeous terraces. The reason for their formation is Henry’s gas law in action which states “the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid” which in this case is the open air. At depth, the superheated water contains lots of dissolved carbon dioxide, which lowers the water pH and allows it to dissolve carbonate minerals it comes in contact with. However, once the water reaches the surface the CO2 degasses because of the much lower partial pressure (concentration) of CO2 in the atmosphere à la Henry’s law. This causes the pH to rise which in turn leads to precipitation of dissolved carbonates such as aragonite and calcite (travertine).

By the way, I have always, always wanted to swim/lounge in one of these sorts of places but have never had the chance. Maybe one day!

Mammoth Hot Springs – travertine terrace – Credit: Joern Behrens (distributed via imaggeo.egu.eu)

Photo of the Week # 41

Matt Herod June 29, 2015

I am furiously writing my Ph.D thesis at the moment. I am close to submitting. I swear! Although, everyone I know says I sound like a broken record when I say this.

Anyway, while I have been doing all this writing I haven’t had much time for blogging, for which I apologize. However, in the interest of breathing some life into this dusty old thing I have decided to re-introduce the photo of the week series. Only this time I’ll be mostly using pics from the EGU geology image repository Imaggeo. It’s fantastic and totally open access!

To get things started lets all admire this really cool example of long range dust transport from the Sahara desert to Greece. While this photo is at the micro scale. I can just imagine this same image as an aerial view of dust blowing across the ocean and the sand in the background as the coastline.

Photo: Konstantinos Kourtidis, Demokritus University of Thrace, Xanthi, Greece Saharan dust was transported northwards, and is visible on this outdoor table in Xanthi, Northeastern Greece. The dust was brought down by a rain shower on the morning of the 23rd of March, and, as the rain evaporated, dust became visible on the objects the rain had fell on. (link)

Geology Photo of the Week #40

Matt Herod July 30, 2013

The 40th edition of the photo of the week highlights the mudlfow from a retrogressive thaw slump near Fort McPherson in the Northwest Territories, where I did field work for a few weeks in 2010 and 2011.

The first photo in this series highlights the slump itself. I took this photo from a helicopter and the entire slump is approximately 1 kilometer wide and has 3 lobes. The mudflow starts where everything converges. I have been told by people who have been back that the slump does not look anything like this today and it is approximately 30-50% larger!

Photo: Matt Herod

The next photo shows the convergence point in the top right and the start of the mudflow as it moves down the valley. There is so much mud that the little stream that once flowed in the valley has been completely dammed and formed a lake.

Photo: Matt Herod

The final photo in the series shows the rest of the mudflow, which extends for about 10 kilometres down the valley.

Photo: Matt Herod