a physical geographer
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Columnar Jointing on the Columbia River 1Part of the Columbia River Basalt Group exhibiting columnar jointing.
Columnar Jointing on the Columbia River 2Another example of columnar jointing in the Columbia River flood basalts.
Devil's TowerDevil's Tower is an igneous intrusion, where magma welled up between sedimentary rocks that have since eroded away. It also exhibits columnar jointing.
Yellowstone StratigraphySome uplift (and exhumation) forming a cuesta and exposing some nice stratigraphy outside Yellowstone NP.
Stratigraphy and TalusA scenic view of a talus slope in Yellowstone NP. Talus is the collection of rock fragments on the slope that have been produced by mechanical weathering.
Mammoth Hot Springs 1Mammoth Hot Springs in Yellowstone NP.
Mammoth Hot Springs 2Profile view of part of Mammoth Hot Springs in Yellowstone NP.
Mammoth Hot Springs 3Limestone dissolved by the hot water underground is deposited as the water is exposed to surface atmospheric conditions, leaving a deposit called travertine.
Mammoth Hot Springs 4The travertine terrace deposits of Mammoth Hot Springs have become over 70 meters thick over the course of about 8,000 years of deposition.
Mammoth Hot Springs 5Travertine deposits can be either fibrous or concentric. Algae and other organisms colonize the surface, adding brown and orange colors.
Limestone in BudapestLimestone exposure in Budakeszi Vadaspark (wildlife park), Hungary.
Mixture of Limestone and Iron OxidesIron (reddish color) from weathering rocks above has been dissolved and then has precipitated out along pathways of water flow.
Calcium Carbonate PrecipitationMiniature limestone precipitation formations (essentially the beginnings of stalactites) on a limestone exposure in Budakeszi, Hungary.
Yellow BoyOften associated with drainage from coal mines, the yellow color is from iron (III) hydroxide precipitating out as the pH rises in the freshwater environment.
Limestone in CroatiaLimestone composing the island of Krk, Croatia. Also a nice example of a Chaparral ecosystem.
Searching for AmethystA popular spot for sifting through broken rock to find quartz crystals near Telkibánya, Hungary. Typically the crystals are Amethyst, which is usually associated with igneous rock formations. However, here among some sedimentary rocks the Amethyst found tends to be paler than its more common version.
Cross-bedding in a Sand Dune 1Similar to streams, the location of erosional and depositional environments can change. A discontinuity in the patterning of the layers can indicate such a shift.
Cross-bedding in a Sand Dune 2It can be difficult to interpret the cross-bedding patterns in a dune. In addition to changes in the environment changing the location of erosional and depositional processes, dunes can have a type of mass settling. These grain flows occur when too much sediment accumulates on the windward side, the angle of repose is reached on the leeward side, and the inside of the dune shifts under the weight.
Ash Pit in Lincoln County, Kansas 1Thick layer of volcanic ash in Kansas. Ash from a volcanic eruption thousands of years ago blanketed the landscape. The ash was then washed into this former lake bed.
Ash Pit in Lincoln County, Kansas 2That this ash was buried in an alluvial environment is evidenced by the intricate cross-bedding.
Ash Pit in Lincoln County, Kansas 3This ash is most likely Pearlette ash, which is tuff from the Yellowstone Caldera when it erupted 640,000 years ago.
Rock City 1A field of curiously spherical rock formations. There are about 200 of these in three clusters near Salina, Kansas.
Rock City 2The rocks are calcite-cemented concretions of sandstone. The similar bedding orientation (horizontal striations) provides a clue that these spheres are erosional remnants formed in situ from the same sandstone formation.
Rock City 3These calcite-cemented concretions are more resistant to weathering than the surrounding sandstone. As the more weatherable material is removed, the more resistant material is left standing.
Striped Flint of PolandA flint nodule within limestone. In this particular flint, the quartz precipitated directly from the seawater, which is unusual for flint. The different coloring of the bands is due to differences in the number and size of pores. Less pore space reflects less light (darker).
Loess KinderNodular limestone concretions that can be found regularly in the calcareous Peoria Loess.
Peoria Loess/Sangamon Paleosol/Loveland LoessThe darker brownish-red band at the base of this image is the Sangamon Paleosol, which formed here in Loveland Loess. That surface was later buried by Peoria Loess.
Paleosol in LoessAnother view of the Sangamon Paleosol, which is between 75,000 to 125,000 years old.
Wolf Creek Paleosols 1The black bands that can be seen in the cut bank are evidence of paleosols in this terrace. An old point bar is in the foreground.
Wolf Creek Paleosols 2Soil that was forming at the surface of the time has been buried by sediments from floods. The black bands are buried A horizons, which form at the surface due to enrichment with organic matter.
Wolf Creek Paleosols 3Gaps between the black bands indicate periods when sediment was being deposited on the floodplain faster than soil could form. The formation of soil indicates a period of stability.
Pre-Illinoisan Till Landscape in KansasField in Kansas with many glacial erratics at the surface. These erratics are especially interesting because they are Sioux Quartzite from more than 400 km (250 miles) away.
Sioux QuartziteQuartzite from a rock formation found in South Dakota, Minnesota, and Iowa. However, this rock was found in Kansas because a glacier carried it here. Glaciers haven't reached Kansas for more than 300,000 years.
Esker Anatomy 1Cross-section of an esker in southeastern Minnesota. Eskers are remnant stream beds that were in/on the ice of a glacier. When the ice melts away, the streambed sediments are laid down, forming a sort of reverse topography.
Esker Anatomy 2A closer look at the fluvial bedding within an esker.
Esker Anatomy 3The images of eskers shown here are from areas glaciated during the Wisconsinan glaciation (~120,000 - 10,000 years before present).
Gleyed TillExposure of till in southern Minnesota.
Outwash and TillCross-section of fluvial deposits that were buried by till.
Development of Creek Bed ArmorConcentration of glacial erratics left behind as the creek carries smaller sediments of the till away. This process will form a hydrologic armor on the stream bed.
Miniature ArmorA miniature example of smaller particles being eroded away, leaving the larger pebbles behind. The larger rocks act like armor, protecting the sediments under them.
Kame 1Meltwater deposited this pile of sediment at the bottom of a moulin.
Kame 2A second view of the same kame in the previous slide.
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