Picture of the Week - Stromatolites

The picture below is from Lester Park, a small roadside rock outcrop a few miles west of Saratoga Springs, NY (here's a brochure from the NYS Museum with directions).  Note the Swiss army knife for scale.

The fossils visible here on this bedding plane of 500 million-year-old limestone (the Cambrian Hoyt Limestone, to geologists) are called stromatolites.  In life, these fossils were made by mats of colonial cyanobacteria - they're sometimes called blue-green algae but they're not algae.

Here's a picture of modern cyanobacteria from Wikipedia.

Looks like pond scum.  Even though it's bacteria, it photosynthesizes - water, carbon dioxide gas, and sunlight are used to create sugars and release oxygen gas as a waste product.

Some 500 million years ago, this area of New York was submerged under warm, shallow water (New York was around 30 degrees south of the equator at this time).  On the seafloor, mats of cyanobacteria happily photosynthesized.  With ocean currents sweeping seafloor sediments around, sediment grains stuck to the bacterial mats.  The bacteria grew up to the top of the sediment layer.  They were buried.  They moved up.  This occurred over and over again to form mounds of finely-laminated structures which eventually became fossilzed as stromatolites.

The first picture showed an eroded rock layer which cut a horizontal plane through the stromatolites.  Below is a picture showing a cross-sectional view as well.

Given their shape, these fossils are sometimes called "cabbage heads."

Besides being neat fossils, what's the significance of stromatolites?  Well, they date back to almost 3.5 billion years - the oldest fossils on Earth - and are still around today.  They were the dominant reef-forming organisms for a couple of billion years until the evolution of multicellular life (while colonial, cyanobacteria are single-celled without a nucleus).  While rare today, they still exist in a few environments - most famously in a location called Shark Bay in western Australia (picture from Wikipedia).

Even more importantly, at least for us, is that cyanobacteria are mainly responsible for Earth's atmosphere changing from one dominated by carbon dioxide gas (like modern-day Venus and Mars), to one with 21% or so molecular oxygen.  We can actually see oxygen levels rising during the reign of cyanobacteria in Earth's ancient oceans since oxygen is so reactive and leaves evidence in the minerals and rocks preserved from those times.

If it wasn't for that ancient "pond scum," we wouldn't exist.

Geologists & Beer

OK, this story's about a month old, but I can't resist being both a geologist and beer aficionado.

Why Geologists Love Beer at Wired Science.

That is one thing I miss from my grad school days - Friday afternoon colloquia and beer.

Newburgh

Excuse me as I make a foray into local social issues today.

The city of Newburgh has been in the news lately.

On January 13, there was a story in the Mid-Hudson News about how Newburgh was going to participate in Orange County's gun buyback program on Saturday, January 16.  Bring your gun down to the police station and they'll give you a Shoprite supermarket gift card worth up to $150.
 
A few hours after this story appeared, a 13 year old stabbed and killed a 17 year old on the streets of Newburgh at 4 in the afternoon.  A number of other kids were involved in the fight and witnesses reported some of them had "clubs."  The local newspaper reported that the school district was going to close all its schools Friday in response (not stated, but obviously worried about violent gang retaliations).
 
Pretty ironic.  The same day the story appears about a gun buyback program - whose aim is to reduce street violence - kids stab each other to death.  Maybe we need a knife buyback?  Of course, we all know the kids would then beat each other to death with clubs.  Buy back clubs and they'd hit each other in the head with rocks.
 
It's not the weapons - it's the people.  I grew up in this area.  When I was a kid, I brought my pocket knife to school (Rondout Valley) every day and no one cared (no one stabbed each other either).  I still carry a Swiss Army knife every day, like most geologists, even though it probably technically violates my college's "weapons" policy.  It's a tool I use almost every day (I fix things a lot).  When I was a kid, everyone had a BB gun by the time they were 10 and many had .22 rifles by the time they were 14 and deer hunting at 16.  I can't remember anyone ever shooting anyone else.
 
Today, New York State makes law-abiding citizens jump through hoops to legally own a pistol.  The process takes 6-8 months, involves photos, fingerprinting, and judge visits, and costs a couple hundred dollars.  Every pistol is registered.  When, where, and how you can carry or use your pistol is governed by a strict (albeit sometimes confusing) set of laws.

Are we safer because of this?  Has gun violence been reduced?  Of course not.  All it does is inconvenience people who would be far more likely to protect you with their pistol than shoot you.  Just the opinion of a card-carrying NRA member who enjoys shooting a .40 Glock (and who thinks the 2nd Amendment to the Constitution is still relevant today).
 
We don't have a gun problem in this country (or a knife problem).  We have a social problem - a subculture of sociopaths that we try to regulate with laws.  Only problem is that sociopaths don't obey laws.

Big earthquake in Haiti

A magnitude 7.0 earthquake occurred today on Tuesday, January 12 at 21:53:09 UTC (4:53 pm EST).  Location was 18.45° N, 72.45° W - about 15 km (10 miles) southwest of Port-Au-Prince, Haiti.  The depth was about 10 km (6.3 mi), a relatively shallow earthquake.

The earthquake basically occurred on a fault (the Enriquillo-Plaintain Garden fault system) associated with the boundary between the North American plate and the Caribbean Plate.  The Caribbean plate is moving eastward by about 20 mm/yr (0.8 in/yr) relative to the North American plate (geologists would refer to this as a left-lateral strike-slip fault).  It sticks, stress builds, then it snaps and moves.

This is a bad one.  Whatever minimal infrastructure Port-Au-Prince had is now likely gone.  The death toll from the quake and its afteraffects will be horrendous.