Evan Gowan’s Post

A new paper published in Icarus describes, maps and dates how glaciers and glacial runoff sculpted the northeastern rim of Mars’ Hellas basin over the last 3 billion years. The paper was authored in part by PSI senior scientist Alan Howard and research scientist Alexander Morgan. Before the research began, the team was intrigued by the dramatic features in Hellas basin, especially in and around Batson crater, which they thought might hint at a history of decaying glaciers. Until now, these features had not yet been adequately described and characterized as being glacial. There are many ways glaciers leave their mark on a landscape. On Earth, glaciers primarily scour the underlying rock as they slowly flow downhill. But on Mars, with its weaker gravity, the physical processes leading to this behavior require thicker ice to achieve. So, the team argues that instead, during a time when Mars was warmer, it’s more likely that meltwater carved the landscape as it flowed beneath and out of glaciers. Learn more: https://buff.ly/46UTT72

2023 also featured many "icequakes" in Alaska — 1,028 to be exact. Measuring icequakes is a powerful tool for remotely monitoring the health of our glaciers. Also known as a glacial quake or "cryoseism" (use that as your next Scrabble word!), ice cracking is registered by seismometers. Most of these events in Alaska result from glacier calving, when a large block of ice breaks off the bottom tip of a glacier. In Alaska, they happen mainly at the tidewater glaciers. They are also mostly seasonal, and peak at different times in different areas—this year, in July and October. Notice that these are shallow (think: surface) events, and they cluster quite tightly where known glaciers and ice sheets reside. [Geography Quiz: what do you think the various acronyms in the map below stand for?]

ICE AGE SANDBLASTING A windkanter (German) or ventifact (English) is a piece of rock with flat or convex facets that were formed as a result of long term exposure to abrasive wind-driven sands. In case three facets are visible (or actually their edges, referred to as 'Kanten' in German), we also call them dreikanter (the German language can be so expressive!). Their facets are often polished and the edges between them are usually sharp. In the Quaternary of northwestern Europe windkanters are characteristic of cold and arid climatic conditions that existed at the end of glacial periods. The most beautiful examples are from finer structured materials like quartzites although examples from other source rocks like granite can also be found. Most windkanters are related to the final phase of the Last Glacial (late Marine Isotope Stage 2) although at some locations, their age of formation might actually be older (a nice cosmogenic dating topic I would say). Exposure seems to be an important factor for their development so the Saalian glacio-tectonic ridges are good sites to hunt for them. I found the nicest ones on the (formerly) exposed flanks of the Saalian Itterbeck-Uelsen glacio-tectonic ridge in the westernmost part of Niedersachsen and adjacent part of the Netherlands (see below). If you have other cool examples of windkanters please post them below :-)! #geology #geoscience #earthscience #mapping #tnogeologicalsurvey #landscape #permafrost #wind #climatechange

- let thy feet repair To Gordale chasm, - - thou mayst perceive The local deity, with oozy hair And mineral crown” William Wordsworth Gordale Scar is a limestone ravine within the Yorkshire Dales National Park, #England, that has inspired poets like Wordsworth and artists like J. M. W. Turner (comment pictures). It is believed that J.R.R. Tolkien had Gordale Scar in mind when he described Helm’s Deep in ‘The Lord of the Rings’. The scar has overhanging limestone cliffs greater than 330 feet (100 m) high with two cascading waterfalls. The British term ‘scar’ refers to a precipitous, rocky place; usually a cliff. The Yorkshire Dales largely consist of a sequence of sedimentary rocks of Ordovician to Permian age. The core area of the Dales is formed by a layer-cake of limestones, sandstones and mudstones laid down during the Carboniferous Period when the area was a shallow sea. Over a period of ~50 million years, a series of limestone beds were laid down composed of the shells of marine organisms and chemical precipitates. The most important of these now form the Great Scar Limestone, a 200m layer of pale grey, well bedded, hard, bioclastic calcarenite. The limestone is mechanically strong, capable of forming vertical cliffs, but it is also soluble. Carbon dioxide in the rain water forms a weak acid (H2CO3) that slowly dissolves calcium carbonate over time as water percolates through faults, joints and horizontal beds. The evolution of Gordale Scar was a complex dance between mechanical and chemical erosion. It began along a major fault at the head end of the chasm that increase permeability allowing solution waters to percolate underground developing small caves. Three successive ice ages scoured the surface, each followed by torrents of meltwater carving the gorge while small caves collapsed underneath. The water that flows over the falls is rich in dissolved calcium carbonate and has precipitated out onto the mossy rocks below to create a soft tufa screen. #Geology #nature

OlD HarrY RoCkS 🍷🤎⚒️ Dorset, England 🏴󠁧󠁢󠁥󠁮󠁧󠁿 (Also in the Dover, UK) (50.6423°N 1.9236°W) 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: Old Harry Rocks are three chalk formations, including a stack and a stump, located at Handfast Point, on the Isle of Purbeck in Dorset, southern England. They mark the most eastern point of the Jurassic Coast, a UNESCO World Heritage Site. 𝗚𝗲𝗼𝗹𝗼𝗴𝘆: During the 𝗟𝗮𝘁𝗲 𝗖𝗿𝗲𝘁𝗮𝗰𝗲𝗼𝘂𝘀, between 𝟭𝟬𝟬 and 𝟲𝟲 𝗺𝗶𝗹𝗹𝗶𝗼𝗻 𝘆𝗲𝗮𝗿𝘀 ago, Great Britain and much of Europe were 𝘀𝘂𝗯𝗺𝗲𝗿𝗴𝗲𝗱 under a 𝗴𝗿𝗲𝗮𝘁 𝘀𝗲𝗮. The sea bottom was covered with 𝘄𝗵𝗶𝘁𝗲 𝗺𝘂𝗱 formed from fragments of 𝗰𝗼𝗰𝗰𝗼𝗹𝗶𝘁𝗵𝘀, the skeletons of 𝘁𝗶𝗻𝘆 𝗮𝗹𝗴𝗮𝗲 that 𝗳𝗹𝗼𝗮𝘁𝗲𝗱 in the surface waters and sank to the bottom and, together with the remains of bottom-living creatures, formed muddy sediments. The weight of overlying sediments caused the deposits to become 𝗰𝗼𝗻𝘀𝗼𝗹𝗶𝗱𝗮𝘁𝗲𝗱 into 𝗰𝗵𝗮𝗹𝗸. British chalk deposits are considered stratigraphically to belong in the 𝗖𝗵𝗮𝗹𝗸 𝗚𝗿𝗼𝘂𝗽. Due to the 𝗔𝗹𝗽𝗶𝗻𝗲 𝗼𝗿𝗼𝗴𝗲𝗻𝘆, a major mountain building event during the 𝗖𝗲𝗻𝗼𝘇𝗼𝗶𝗰, the sea-floor deposits were raised above sea level. The cliffs' chalk face shows 𝗵𝗼𝗿𝗶𝘇𝗼𝗻𝘁𝗮𝗹 𝗯𝗮𝗻𝗱𝘀 of 𝗱𝗮𝗿𝗸-𝗰𝗼𝗹𝗼𝘂𝗿𝗲𝗱 𝗳𝗹𝗶𝗻𝘁 which is composed of the remains of 𝘀𝗲𝗮 𝘀𝗽𝗼𝗻𝗴𝗲𝘀 and 𝘀𝗶𝗹𝗶𝗰𝗲𝗼𝘂𝘀 𝗽𝗹𝗮𝗻𝗸𝘁𝗼𝗻𝗶𝗰 𝗺𝗶𝗰𝗿𝗼-𝗼𝗿𝗴𝗮𝗻𝗶𝘀𝗺𝘀 that hardened into the microscopic 𝗾𝘂𝗮𝗿𝘁𝘇 crystals.White chalk is composed almost entirely of calcium carbonate. This calcium 𝗰𝗮𝗿𝗯𝗼𝗻𝗮𝘁𝗲, a very pure type of limestone, consists of 𝗯𝗶𝗹𝗹𝗶𝗼𝗻𝘀 of 𝗺𝗶𝗰𝗿𝗼𝗼𝗿𝗴𝗮𝗻𝗶𝘀𝗺𝘀 including 𝗳𝗼𝗿𝗮𝗺𝗶𝗻𝗶𝗳𝗲𝗿𝗮 and calcareous algae, coccoliths and 𝗿𝗵𝗮𝗯𝗱𝗼𝗹𝗶𝘁𝗵𝘀. 📷-© @henry_do[IG] #chalk #dover #fossil #sedimentary #cliff #seaerosion #europe #formation #geology #iitism

Pamukkale, #Turkey is renowned for having the most beautiful and extensive travertine pools in the world. It is the key location for ‘travitonics’ (travertine tectonics) and includes morphologies associated with travertine deposits accompanied by active faults. In addition to the stunning pools, features include terrace-mound, fissure-ridge, range-front, eroded-sheet and self-built channel travertines. Fissure ridges form from spring discharge along joints or faults while self-built channel form by flowing thermal waters (comment photo). Along a 6 km stretch of the Pamukkale plateau, the site features a spectacular array of white calcite terraces and rimstone pools cascading over 200-meter-high cliffs on the uplifted side of the Pamukkale fault. Named for the bright white rocks, Pamukkale translates as “cotton castle” or “cotton palace.” Travertine deposition has been occurring in the area for at least 600,000 years during the Pleistocene epoch. However, much of the deposition at Pamukkale has occurred in the past 50,000 years. Research suggests the current hydrothermal and depositional system was established after a seventh-century earthquake. Travertine is a type of terrestrial limestone formed by the rapid chemical precipitation of calcium carbonate from fresh water, both surface and ground water. The best examples are formed around hot springs. At Pamukkale, the landscape has been developing since the middle Pleistocene by precipitation of calcium carbonate from saturated geothermal waters charged from a fault scarp with flows from 17 hot springs at temperatures ranging from 35 to 100°C. Groundwater circulation through limestone bedrock causes the calcite supersaturation. The hot springs and thermal pools at Pamukkale have been a spiritual, cultural, and recreational destination for thousands of years. In the second century B.C., the ancient Greco-Roman city of Hierapolis was built atop these terraces. Pamukkale travertine is the most visited international tourist destination in Turkey. Top Photo - Terrace pools at sunset (Archive of Ministry of Culture and Tourism). #Geology #nature

From vibrant metals and gemstones to prehistoric fossils and natural hot springs, these areas are rich in natural wonders that tell a story spanning millions of years. Read more in our newest blog at the link below. #lacyrichterrealtor #montanarealestate #LakesideMontanaRealestate #ListingagentMontana #SellingagentMontana #lacyrichter

Part 2: Exploring the Geomorphology 🏞️ The new instalment of GEOLOGICAL WINE MAP by Enographiae, focus on the captivating landscapes of the Champagne Region! Dive into the dynamic terrain of the Champagne region, where low-height plains and plateaus paint a picturesque canvas of geological diversity. Along the southeastern and eastern perimeters, the gradual erosion of geological strata has sculpted slopes gently sloping towards the basin's interior and steeper inclines towards the exterior, forming iconic cuestas like the Bar coast. Witness the resilience of limestone and chalk on the plateaus (Barrois), resisting erosion and maintaining nearly horizontal or gently undulating surfaces, while rivers carve deep valleys into the terrain. The plains, whether wet or dry, unveil tales of soft terrains easily cleared or enduring rocks that have withstood the test of time. For a deeper understanding of the geological marvels shaping Champagne's landscapes, click the link urly.it/3_gfp #Champagne #Geology #Map #Wine #Topography #Vineyard #GeologicalMapping by #Enographiae

From vibrant metals and gemstones to prehistoric fossils and natural hot springs, these areas are rich in natural wonders that tell a story spanning millions of years. Read more in our newest blog at the link below. Are you ready to start Living Good?

Pumice vs. Scoria: What's the Difference? As a geologist, understanding the distinct characteristics of volcanic rocks is essential, especially when working with lightweight aggregates like pumice and scoria. # Pumice is a light-colored, highly vesicular volcanic rock formed from explosive volcanic eruptions. Its key characteristics are: Composition: Rich in silica, making it lighter in color. Texture: Highly porous with a frothy texture, it can even float on water! Formation: Rapid cooling of gas-rich, felsic lava traps air bubbles, giving pumice its lightweight and airy nature. Use: Often used in construction (lightweight concrete), horticulture, and even skincare (pumice stones). # Scoria, on the other hand, is a darker, heavier volcanic rock with larger vesicles. Its distinguishing features include: Composition: Rich in iron and magnesium, resulting in its darker, reddish or black hue. Texture: Less porous and denser than pumice, it sinks in water. Formation: Forms from mafic lava with fewer trapped gases, giving it a rough, bubbly surface. Use: Commonly used as a landscaping material, in drainage systems, and as a heat insulator. In short: Pumice: Lighter, frothier, floats. Scoria: Heavier, denser, sinks. Both are fascinating examples of volcanic processes, but their distinct properties make them suited for different applications. #Geology #VolcanicRocks #Pumice #Scoria #EarthScience #MaterialsScience #GeologyRocks #Geologist