weathering – Geobites

January 26, 2023January 26, 2023

How plants left a mark on history

Featuring image: Plants slowly eroding limestone. Picture from Jon Sullivan, public domain (C0).

Paper: Composition of continental crust altered by the emergence of land plants

Authors: C. J. Spencer, N. S. Davies, T. M. Gernon, X. Wang, W. J. McMahon, T. R. I. Morrell, T. Hincks, P. K. Pufahl, A. Brasier, M. Seraine and G.-M. Lu

In the winter of 1990, the first Voyager spacecraft looked over its shoulder and snapped an iconic photo of Earth as a ‘pale blue dot’ in the vast cosmos. But when you look at it from Space, there is another very important colour: green. Plants cover a major portion of the landmasses. Besides bringing their bright chlorophyll colour to the continents, new research by Spencer and co-authors finds that plants have also slowly changed the composition of the Earth’s crust over hundreds of millions of years.

In a recent study, Spencer and co-workers were able to connect the development of land plants to changes in the geochemical composition of crustal rocks through the effects that plants had on landscapes, weathering, and sediments. Land plants arose during the early Ordovician period, about 440 million years ago, and today they cover approximately 84% of Earth’s landmasses. After they spread all over the continents, plants started to heavily influence the sedimentary cycles between continents and oceans.

December 7, 2021December 7, 2021

Carbon to carbonates: capturing CO2 with rocks

Featured image: a field of basalt in Hawai’i Volcanoes National Park (National Park Service, public domain)

Paper: Potential CO2 removal from enhanced weathering by ecosystem respnses to powdered rock
Authors: Daniel S. Goll et al.

In the 2015 Paris Agreement, nations pledged to work toward a common goal of limiting global warming to less than 2°C compared to pre-industrial times. The Agreement doesn’t specify how the signatories should do this, though: levy a carbon tax? Shut down coal-fired power plants? Use a stainless steel straw? According to the best available climate science, we will need to be doing all of the above and then some. In fact, meeting the target of the Paris Agreement will require negative emissions, removing greenhouse gases from the atmosphere via some form of Negative Emissions Technology (NET).

August 11, 2021August 11, 2021

Landscapes get depressed too: limestone depressions pattern a wetland landscape

Aerial view of the Big Cypress National Preserve

Feature Image: Limestone depressions cover the landscape in the Big Cypress National Preserve in Florida, USA. (C) Google.

Article: Competition Among Limestone Depressions Leads to Self‐Organized Regular Patterning on a Flat Landscape
Authors: Dong, X., Murray, A. B., & Heffernan, J. B.

Patterns are abundant in nature, from evenly spaced termite mounds and vegetation patches to repeating series of ridges and valleys to sand dunes. The questions of why these patterns are so uniform and why they are found in disparate settings has been the subject of intense scientific interest over the last decades. Mathematical tools have given scientists the ability to study these “complex systems,” where behavior of the whole system emerges from interactions between smaller parts. While many different systems have been studied, recently researchers from the Duke University and the University of California at Davis investigated a patterned landscape with mysterious origins: the large, evenly spaced depressions in limestone bedrock that cover nearly 3000 square kilometers of the Big Cypress National Preserve in the Florida Everglades.

December 29, 2020December 29, 2020

When Lightning Strikes! Fulgurite Formation and Earth’s Weather

Paper: Lightning-induced weathering of Cascadian volcanic peaks

Authors: Jonathan M. Castro, Franziska Keller, Yves Feisel, Pierre Lanari, Christoph Helo, Sebastian P. Mueller, C. Ian Schipper, Chad Thomas

The bright flashes followed by the loud thunderclaps of large storms are inherently transient, but a recent study by Castro et al proposes a new approach to investigating the history of storm activity and extreme weather events on Earth: through fossilized lightning strikes, or fulgurites.