Loose_Grip/Pete's photos with the keyword: geology

It's difficult to capture the depth of the "Big Hole" in Kimberley but the height of the buildings give an idea of the scale. It's a real vertical wall of rock. Kimberlite, an ultramafic igneous rock and a rare variant of peridotite, is most commonly known to be the main host matrix for diamonds. It is named after Kimberley where diamonds were mined from this hole. Kimberlite occurs in the Earth's crust in vertical structures known as kimberlite pipes, as well as igneous dykes and can also occur as horizontal sills. The consensus on kimberlites is that they are formed deep within the mantle, hence at high temperatures and pressures. HWW to everyone. Have a great day!

The Permian El Capitan reef complex in the Guadeloupe Mountains on the Texas-New Mexico border. After the flight from Dallas to El Paso we transferred to the tour bus for a geological field trip around West Texas. As an undergraduate I wrote a long essay on carbonate reefs referring to the Guadalupian El Capitan as the prime ancient analogue of modern build-ups. It was a real buzz to actually visit it and hit the rocks with a hammer!

Pure geology. An absolute classic outcrop example to show the difference between sedimentary dip (almost vertical) and cleavage (almost horizontal) in deformed metamorphic rocks, Devonian Polzeath Slates in this case. Seen on Polzeath beach.

Mobil Oil Canadian Tectonic Seminar. The Plateau Mountain Ecological Reserve (although it wasn't called that in 1982) is quite a windswept place at a height of over 8000ft. We made a lunch stop here. The grass covered patterned ground in front is caused by periglacial conditions which shatter the Permian Rocky Mountain quartzite, by thawing & refreezing, into polygonal patterns. This is the crest of an anticline and the quartzite is almost flat-lying. It may be Ecological but in fact it is home to the highest gas well in Canada - Savanna Creek-3A drilled in 1952 at 8132 ft. East of the McConnell Thrust, the zone of highly imbricated and deformed Mesozoic to Tertiary rocks around 50 km wide, forms the Foothills where the Lower Carboniferous & Devonian oil and gas fields are found. The mountains in the background about 9 miles away to the west are in the High Rock Range, on the Alberta/British Columbia boundary, which lies above the Lewis Thrust and forms the Continental Divide. The peaks are in the 9000-10,000 ft range. Mount O'Rourke, left, Mount Pierce, centre, the highest peak right of centre is Mount Farquar with Mounts Holcroft & Scrimger to the right

The scale of the fabulous compressional tectonic features of the Front Ranges of the Rocky Mountains are definitely best appreciated from the air and the participants in our Mobil Oil field seminar were privileged to have an overflight of the Rockies on the last day of the course. I was living in The Hague, the Netherlands, at this time and working on the sub-surface Alpine tectonics in the North Sea. Superficially the Geology of Holland is pretty boring but 1000m below the surface in the Dutch offshore all hell breaks loose and believe it or not it looks just like this! It could be a seismic cross-section through the Lower Cretaceous oil fields in Block Q1. The subsurface oil and gas fields in the Foothills west of Calgary are trapped in analogous thrust anticlines.

The Schynige Platte narrow-gauge rack railway with an electric engine approaching the summit station. Some pretty impressive Alpine geology in the background

Me & Francoise getting a close look at the sulphur around the fumerole of Mount Sibyak volcano.