Geobulletin alpha

Little River heads to Environmental Education Association conference 

In an effort to share our interest in outreach environmental education with others, we are attending the Environmental Education Association of Illinois Annual Conference at the Touch of Nature Environmental Center in Makanda, Illinois.The conference began today and runs through Saturday, April 11. Amanda and Jim will be there for Friday’s events, which include an exhibition of one of our Emriver Em2 geomodels facilitated by Amanda.This year’s theme is Bridging Gaps Under Southern Skies, [...]

Field Photo: A Bend In A Himalayan River 

I took this picture of a meander and a point bar deposit on the road from Munsiyari to Bageshwar along a section of the Sarayu river traversing a section of the Lesser Himalayas. It shows the classic meander landform of cut erosion along the outer bank  and deposition along the inner bank. Land pressure is high in the Himalayas too and the point bar deposit has been cultivated. Another

Died This Day: Giovanni Arduino 

Arduino (Oct. 16, 1714 - March 21, 1795) was an Italian geologist, known as the father of Italian geology, who introduced the terms Primary, Secondary, Tertiary, and Quaternary in 1760 to classify four broad divisions of the Earth's rock surface, each earlier in deposition. Within each he recognized numerous minor strata, and had a clear paleontological interpretation of the age sequence of

Golden Triarthrus eatoni trilobite from the Whetstone Gulf formation 

A recent addition to my collection is this piece of black shale from the Whetstone Gulf formation, Ordovician (Sandbian stage) near Worth, NY. It's been prepped to expose some exquisitely preserved Triarthus eatoni trilobites cavorting on an algal frond. The fossils are preserved by pyrite and minute details of the trilobites are present such as their antennae and legs. Some specimens also have the gills and mouth parts preserved. This rock comes from a layer similar to the one exposed in [...]

Leiorhynchus multicostus brachiopods from the Levanna Shale 

I came upon this plate of shale in a small quarry near the town of Fayette in New York. It comes from the Levanna Shale of the Skaneateles Formation and is covered with brachiopod fossils called Leiorhynchus multicostus (aka Eumetabolatoechia multicostatum). Leiorhynchonellid type brachiopods are often common in black shales which indicate that they were tolerant of conditions with lower oxygen content. In this case there must have been a period or time where the conditions were right and the [...]

Monday paper: Changes in soil carbon sequestration in Pinus massoniana forests along an urban-to-rural gradient of southern China 

Chen, H., Zhang, W., Gilliam, F., Liu, L., Huang, J., Zhang, T., Wang, W., Mo, J. 2013.  Changes in soil carbon sequestration inPinus massoniana forests along an urban-to-rural gradient of southern China. Biogeosciences 10, 6609-6616. DOI: 10.5194/bg-10-6609-2013 Abstract Urbanization is accelerating globally, causing a variety of environmental changes such as increases in air temperature, precipitation, atmospheric CO2, and nitrogen (N) deposition. However, the effects

Annotating some Zion cross-bedding 

I got a comment the other day on an old post on this blog, one showing beautiful cross-bedding at Zion National Park. These are dune sands – windblown at the time of deposition, and cemented in place for millions of years thereafter. These are petrified sand dunes! The commenter asked about annotation, so I took ten minutes and modified the picture to highlight the key features as I saw them.

Sequence Stratigraphy 

Describe the sequences as described by Sloss (1963) and discuss the possible controls on their deposition. Sequence stratigraphy is a system of linking unconformity-bounded sediment packages to global events to temporally correlate sedimentary units across lithographic boundaries. This is important … Continue reading

Then as Now: Iceberg Discharges During Last Glacial Maximum Driven by Oceanic Circulation Changes 

Iceberg discharges of the last glacial period driven by oceanic circulation changes Authors: Alvarez-Solas et al Abstract: Proxy data reveal the existence of episodes of increased deposition of ice-rafted detritus in the North Atlantic Ocean during the last glacial period interpreted as massive iceberg discharges from the Laurentide Ice Sheet. Although these have long been attributed

Guest Post: Glaciation in Glacier National Park 

This is the first of several guest posts that will appear here this week, all written by students who participated in this past summer’s Regional Field Geology of the Northern Rocky Mountains course. by Madeleine Rushing Sedimentary deposition typically is seen as horizontal strata, layered one on top of the other with oldest deposits on the bottom, getting progressively younger with each layer. Which makes sense, as that is how

Extreme Mountains, Extreme Sedimentation 

A primary goal of Exp. 341 is to examine how changing the mass balance of sediments, i.e. decreasing the amount of sediments on land by glacial erosion and increasing the amount of sediments in the ocean via deposition, has influenced exhumation of the St. Elias Mountains. Southern Alaska is an ideal location for this study because of the huge amount of uplift in the Wrangell-St. read

Periods Of Non Deposition of Sediments Are Transformative And Useful Recorders Of History Too 

Came across this interesting article published a few months ago in Sedimentology: Deciphering condensed sequences: A case study from the Oxfordian (Upper Jurassic) Dhosa Oolite member of the Kachchh Basin, western India -Mathhias Alberti, Franz Fursichi, Dhirendra Pandey Properties of sediments and sedimentary rocks tell us a lot about the geological history of the depositional basin as

Geo-gardening 

Geo-gardening - Sunday 3rd February 2013On Sunday 3rd February 2013 a Joint Gardening Force (JGF) from Friends of Trendlewood Park (FoTP) and Avon RIGS Group descended on Trendlewood Quarry in Nailsea and proceeded to spend a few hours clearing ivy and other encroaching vegetation from the lower parts of the quarry face in three areas.                                              [...]

Friday Field Photo #145: Convolute Lamination in the French Alps 

This week’s Friday Field Photo is from Eocene Grès d’Annot Formation exposed in the mountains of southeastern France. The upper part of the bed displays some attractive convolute lamination. Originally horizontal structures were deformed in a “soft” way very soon after deposition (while still a mixture of sediment and water). This  structure is very common

Pleistocene Sample indicating 450m lift 

A sample from the Peloritani mountains in the northeastern part of Sicily, Italy indicates that the terrain has been lifted by 450m or more within only 1,8 Mio. years since the early Pleistocene. The material is taken from the Salice Outcrop lying today at 340m above sealevel. It contains several Globorotalia inflata, which first appeared in the latest Pliocene/Early Pleistocene. Geological studies place the Salice outcrop into the Early Pleistocene spanning from 1,8-0,8 million years BC.Read [...]

Cabinets of curiosities #4: Classification and Collection 

The naturalists of the Renaissance were obsessed with the idea to collect and describe all the secrets of earth, polymaths by passion, however only some men achieved so much confidence in this task as Conrad Gesner (1516-1565) as he avidly collected and immortalized such things as words, animals, plants and rocks. Other tried to classify catastrophes and explain the origin of earthquakes.But not only nature, also time should be distinguishably and labelled adequately - in a letter to his fellow [...]

The Big Bentonite just got smaller 

The Shenandoah Valley of western Virginia records the switch in late Ordovician time from passive margin sedimentation associated with the Sauk and Tippecanoe epeiric seas, to active margin sedimentation associated with the onset of the Taconian Orogeny to the east. Higher up in the stack, a similar pattern is seen: a return to passive margin sedimentation with the deposition of the Helderberg Group of limestones, and then more active margin

The Long Beat of Rhythmic Sedimentation 

The history of Earth is recorded in rocks. And the history of events and conditions at the Earth’s surface, including the origin and evolution of life, is recorded in sedimentary rocks. The deposition of clastic sediments (broken pieces of other rocks in the form of sand, silt, and mud) and precipitation of chemical sediments from solution

GeoVoices: Education and Training of Geologists; Is Field Camp Still Relevant? 

An article in the Winter 2011 AGI GeoSpectrum magazine caught my attention. It was a summary of a discussion on the AIPG LinkedIn group about the importance of a geology fieldcamp in your education. I can't say I was surprised, but one comment caused me a little dissappointment: Field camp separates us from the engineers. I think I understand where the comment is coming from, I would probably agree that most civil geotechnical engineers don't have any kind of field geology course, or any [...]

Milankovitch Cycles and Carbonate Deposition 

Over at Open Mind, Tamino has written a series of excellent posts on Milankovitch climate cycles and how they influence the growth and decay of ice sheets. Milankovitch cycles are orbital cycles which result in periodic fluctuations in the amount of solar energy received by the earth. Three types of cyclical changes in the earth's movement around the sun, eccentricity, obliquity and