The Earth Story

The New Madrid Seismic Zone About once a year, residents of the counties at the border between Kentucky, Tennessee, Missouri, and Arkansas will feel the ground roll beneath their feet. This image maps out the location of earthquakes in this area over a 30-year period and clearly illustrates a major feature: the New Madrid Seismic Zone. This zone produces about 1 quake that can be felt per year in addition to many small earthquakes…and has historically produced really big ones.

Ancient Ripples These layers are pretty neat when you can find them. This is a surface in the Tradewater Formation of Southern Illinois covered with ripples. Ripples like these are characteristic of the edge of ocean basins or lakes, where wave action and water currents can move the sediment around. Preserving the ripple marks requires covering them without destroying them – an event like a storm that brings a lot of extra sediment can bury previously-formed ripples without destroying them. Finding these ripple marks establishes that the sediment was deposited near a shoreline, in a setting with active currents. The Tradewater formation is Pennsylvanian in age, formed about 350 million years ago when much of Central North America was submerged in a shallow ocean. The formation also has a number of coal beds within it, formed as the seashore migrated in and out as sea level changed. Ripples like these can be useful for a geologist. If rocks have been folded it can be difficult to tell which side of a unit was the top – ripple marks only form on the top of a unit and so can be used to say which direction was “up” (although there can be casts of the ripples formed from the sediments that touch these ripples). Ripple marks can sometimes even tell where currents were flowing, how strong currents were, and how deep the water was. -JBB Image credit: https://flic.kr/p/ozbh9N Read more: http://pubs.usgs.gov/pp/p1625d/Chapter_C.pdf http://bit.ly/1Lz7joi http://digital.library.okstate.edu/oas/oas_pdf/v22/p145_146.pdf http://bit.ly/1FzNwn2

Ancient Ripples

These layers are pretty neat when you can find them. This is a surface in the Tradewater Formation of Southern Illinois covered with ripples.

Ripples like these are characteristic of the edge of ocean basins or lakes, where wave action and water currents can move the sediment around. Preserving the ripple marks requires covering them without destroying them – an event like a storm that brings a lot of extra sediment can bury previously-formed ripples without destroying them.

Finding these ripple marks establishes that the sediment was deposited near a shoreline, in a setting with active currents. The Tradewater formation is Pennsylvanian in age, formed about 350 million years ago when much of Central North America was submerged in a shallow ocean. The formation also has a number of coal beds within it, formed as the seashore migrated in and out as sea level changed.

Ripples like these can be useful for a geologist. If rocks have been folded it can be difficult to tell which side of a unit was the top – ripple marks only form on the top of a unit and so can be used to say which direction was “up” (although there can be casts of the ripples formed from the sediments that touch these ripples). Ripple marks can sometimes even tell where currents were flowing, how strong currents were, and how deep the water was.

-JBB

Image credit: https://flic.kr/p/ozbh9N

Read more: http://pubs.usgs.gov/pp/p1625d/Chapter_C.pdf http://bit.ly/1Lz7joi http://digital.library.okstate.edu/oas/oas_pdf/v22/p145_146.pdf http://bit.ly/1FzNwn2

The roads of Illinois. You can tell how recently the landscape was glaciated by how many hills there are - this area probably was not ice covered during the last glaciation, but was glaciated before that. Since then, rivers and topography have developed.

A white stripe across the landscape The path of this snow laden earlier storm this month ran across the Northeastern USA from the Midwest to the Atlantic leaving behind a clear mark of its passage snapped by the MODIS instrument aboard NASA's TERRA satellite. The band of the storm's passage is clear, with 45cm dumped on Iowa. Loz Image credit: NASA

Sunrise over Chicago

Wall of water marches across buildings on its way to Chicago’s Grant Park and Lake Michigan.

Drone flyover of the edge of the Thornton Quarry on the south side of Chicago - a gigantic hole in the ground from which the limestone that constructed many of Chicago’s Roads was pulled. Now, the gigantic pit has been repurposed into a flood control feature, with water flow at the bottom likely creating the patterns seen here

Midwest Meteor

Sunday night, hundreds of witnesses across parts of the US Midwest were treated to a short but spectacular light show when a fireball lit up the nighttime sky. The bright green meteor was reported over Wisconsin at 1:27am CST, waking some locals up with a sonic boom.

Fireball is a term used to describe meteors that are unusual bright and can be seen over a wide area. In this case, sighting reports came in mostly from Wisconsin and Illinois, but also from several other surrounding states and into Canada.

The color is influenced by the composition of the meteor as friction from going through the atmosphere heats it up. Green is typically an indication that nickel is present in the rock.

Fireballs generally aren’t large enough to survive the trip through our atmosphere. NASA Meteor Watch estimates it was about 272 kg (600 lbs.) in weight and 0.6 meters (2 feet) in diameter. It’s thought to have exploded over Lake Michigan. Doppler weather radar recorded fragments falling into the water at the meteors last known point.

Video Credit: Glendale Police Department https://www.facebook.com/GlendaleWiPD/

References: http://bit.ly/2lhVXOA http://n.pr/2lgSfWf http://neo.jpl.nasa.gov/fireballs/

Strange reflections

As an airliner approached its landing at Chicago's O'Hare airport a rare glimpse of a reflected upside down city leapt forth from a break in the dusk time clouds, looking like something that should belong in the land of Faerie. In fact, the city's shadow was cast onto Lake Michigan by the lowering sun, and reflected in the still waters along with the solar orb's orangey glow, appearing to the passenger as an upside down city hanging off the clouds..

Loz

Image credit: Mark Hersch via APOD

A 60 day paddling trip down the Mississippi River condensed into 60 photographs. (Spot your city?)