Our Window on Nature

Years ago we were hiking high on Mount Ranier in Washington State when we saw a plume rising from Mount St. Helens far in the distance. It had to be some time after 1980, because that is when the volcano become active once again. Our first thought was of another eruption. Training our binoculars on the volcano, we finally decided it must be dust from a rockfall inside the dome.

The original eruption in 1980 reduced the height of Mount St. Helens by 1,314 feet, removing 3.7 billion cubic yards of material. But now the volcano is growing again, and it is the upward pressure that is causing the present tremors.

The volcano became active most recently in September of 2004, and since that time there have been many small earthquakes, each with a magnitude of less than 2.0 on the Richter scale. Now there are multiple quakes each day. Scientists say they don’t think an eruption is likely at the present time, but no one can tell for sure. Locally the small quakes are being called drumbeats, and the cause of the minor shaking is part of an ongoing dispute.

One group thinks that a “plug” is being pushed up — then released, and that rock rubbing against rock is causing the quakes. Another argues that it is steam inside the volcano and they say

vibrations in a steam-filled horizontal fracture about 330 feet (100 meters) beneath the crater floor are causing the drumbeats. There’s plenty of water in the ground, and there’s plenty of heat.

When the weather warms up, you can actually visit Mount St. Helens, but in the meantime (or if you don’t want to get that close), here is a WebCam view of the volcano. Just don’t bother looking at night, since the view is live.

NASA released several photos today showing the possibility of water on Mars. They didn’t actually find the water, but by comparing photographs taken in August 1999 with the same location in September 2005, there is exciting news. The new picture shows a major change that occurred some time in the last five to seven years. According to the NASA website

The atmosphere on Mars is so thin that liquid water cannot persist at the surface. However, researchers propose that water could remain liquid long enough, after breaking out from an underground source, to carry debris before totally evaporating and freezing.

The photo at the left shows the before and after pictures, and scientists believe the several hundred foot long white streak was caused by flowing water. If this is the case, it increases the possibility of finding microbial life on Mars.

Watching the night sky can be fascinating any time of year, but during meteor showers it takes on the characteristics of a fireworks show. But just what is the object that causes all the excitement?

Let’s start with the name, because it changes depending on where you find it. While they are still out in space they are called meteoroids. As they flash though the sky on their way to the earth they are called meteors. And if they don’t burn up in the atmosphere, when they reach the ground their name changes to meteorites.

Some meteors are made up of a stony substance, mostly silicate materials. Others may be an iron-nickel combination. Or perhaps it is a blend of the two. But this is material from outer space that intersects our path as the earth travels around the sun.

A few people collect meteorites as a hobby while others do it for the sake of science. The problem with meteorites, unless you just buy them on EBay, is to find them. To be successful you either need a lot of luck or must understand why certain locations are better than others.

Meteorites deteriorate just like other rocks and minerals on earth, but in very dry areas this process can take millennia. So when scientists want to search for these space visitors, they usually head toward the South Pole.

At first thought this might seem a strange place to look for a dry climate, but the pictures of ice that come to mind ignore the fact that the Antarctic is classified as a desert because of the lack of moisture – an almost complete lack of liquid water. This means that rocks, or in this case the meteorites, will resist deterioration for a very long time.

The average age of a meteorite found in Antarctica is about 4.5 billion years, and scientist say that most of these discoveries have been on the earth for between 25,000 and 65,000 years.

Since 1976 the Antarctic Search for Meteorites (ANSMET) has sent 20 search teams to Antarctica, collecting over 10,000 meteorites. A combination of wind conditions and shrinking ice packs provide concentrations of these space fragments found nowhere else.

There is a real advantage to looking for meteorites on an ice pack. In most areas of the world these hunks of rock can easily disappear – buried in the ground, behind a bush, or hidden deep in a forest. But on an ice pack, there is almost no place to hide. Add to this the contrast between a black piece of rock and a white background, and an ice field becomes the perfect area to search.

Most meteorites come from debris caused by collisions of larger bodies in the asteroid belt, but some are actually from the moon or from Mars, blasted into space by a grazing blow from another space visitor. Those from the moon were identified by comparing them with rocks collected by astronauts, while fragments from Mars were determined when the gasses held inside their bodies matched those collected by robotic travelers to the red planet.

If you can’t afford the time for a quick trip to McMurdo Station in Antarctica, you can join them vicariously on the ANSMET website at http://geology.cwru.edu/~ansmet/index.html. Lots of pictures and a great explanation of what they do.

At one time we lived next to an earthquake fault. It ran through a golf course just over our back fence. Of course, we lived there for several years before learning of its existence. A big quake came long after we had moved away.

Some years later we found ourselves in a similar situation while staying in a campground in central California. We were talking to some college students working on a surveying project – tracking long-term movement of the San Andreas Fault. They told us the fault zone ran directly under where we had our motorhome parked. Oops….

Different parts of the country have different hazards, whether it is tornados, hurricanes, or earthquakes. And usually the ones you fear most are those that occur in someone else’s backyard. Those nearby are the ones you understand, and I suppose that leads to a kind of acceptance. Living in the West we have become accustomed to an occasional shaking.

But the West doesn’t have all the excitement. Although the four largest earthquakes in the last several hundred years all occurred in Alaska, number five was the New Madrid, Missouri, quake in 1811. It wasn’t the strongest, but it was felt over the widest area. For some reason, the geology in the eastern United States allows shock waves to spread over a greater distance.

A recent study by the Nevada Seismological Laboratory at the University of Nevada listed the various states in order of their average seismic activity. Not surprisingly the top contenders were Alaska, California, Nevada, and Hawaii.

Want to get away from earthquakes? They can occur anywhere, but the two states that seem to have the fewest are Florida and North Dakota. However I’ve heard some interesting stories about hurricanes and tornados.

It’s a truism that living organisms require light to survive, yet you’ll find exceptions to the rule if you look in the right places. Deep within a cave, without the faintest glimmer of light, life goes on. But it is life with a difference.

Our first experiences underground took place in Mitchel Caverns beneath the vast expanse of the Mojave Desert. The combination of exotic rock formations and the eerie silence made cave converts out of us at once. But at that time we had barely heard of creatures that spend their lives in caves. (Read the rest …)