The meteor craters of southern Germany

This blog entry was written to accompany my podcast for the September 5, 2010 broadcast of the 365 Days of Astronomy. The podcast can be listened to here.

One of the high points of my stay in Germany recently was a visit I made to Nördlingen on the border between the provinces of Bavaria and Baden-Württemberg in southern Germany. It’s a beautiful place. It is enclosed by a defensive wall that dates back to the 14th Century – there are only three towns in Germany with this claim to fame. All the buildings are full of character. The town was the site of two battles during the Thirty Years War and were it not for the cars and the shops, you could easily imagine yourself in another time, another era.

But beautiful and all though the town is, this is not the reason I went there. It’s Nordlingen’s surroundings that interested me the most. The town is located in a region known as the Ries: a round, flat plain with an approximate diameter of around 23 km (15 miles).  This area is quite different to the surrounding countryside as the following scale model clearly indicates.

For many centuries, the prevailing idea about how this geological feature came to be was that it was an ancient volcanic caldera. The trouble was that much of the boulders and debris surrounding the  region were of non-volcanic origin. Many ideas were presented as to how this material got there, but it’s didn’t fully add up. The origins of the Ries remained controversial until fifty years ago.

Enter Eugene “Gene” Shoemaker. Gene was an astronomer and he had a few questions. When he looked at the Moon he saw a landscape quite different to the Earth. Everywhere on the Moon he saw craters. Big craters, small craters, enormous craters. Why then was the Earth practically devoid of them? Was it credible that the Moon could be subject to the slings and arrows of outrageous impacts while its larger sister, our planetary home, missed them all? He was convinced that the evidence for impact craters must exist on Earth, but where were they all? Gene had a good idea what kind of material would be created when a large object hit the Earth. It was just a matter of finding it.

Gene found the answer in Nordlingen. During a visit to the town in 1960 he became fascinated by the stones of St Georg’s Church in the centre of the town. He immediately realised that the church walls contained coesite, a material only created as a result of a massive meteorite impact. The rock had been mined locally from the Ries. This lead to a simple, stark conclusion. The Ries had been formed as a result of a gigantic meteor impact. “It was the first big impact crater on the Earth that we could prove was an impact crater, and that just changed the whole ballgame”, said Shoemaker.

Here is what we know. 15 million years ago, two large objects, one measuring up to 1km in diameter, crashed into southern Germany. The large object hit Nordlingen. Hitting the ground at a speed of 45,000 km per hour, it punched a hole 4km deep into Earth’s crust, vaporising on impact. The surrounding rocks were compressed to a quarter of their size by the impact and they responded with an explosion measuring 18,000 megatonnes of TNT, hundreds of times larger than the greatest nuclear bomb ever detonated on this planet. An enormous shock wave killed all living things for a hundred kilometers in every direction with devastating effects felt much further afield. A mushroom cloud 30km high was generated. Much of this cloud, composed of melted rock from deep within the crust, subsequently fell back to earth, covering the crater and the region around the Ries with a material known today as Suevite. The church of St Georg in Nordlingen is built from this material.

A massive amount of bedrock was ejected ballistically, forming rocks known as Bunte Breccia. The deepest rocks landed close to the impact zone while rocks close to the surface were hurled over great distances. Some limestone blocks have been found 70km from the crater while glassy rocks known as Moldavites have been discovered 400km away in the Czech Republic.

The 1km deep hole left by the impact became a lake and life returned to the Ries. Over time the lake itself became clogged with sediment and subsequent glaciations flattened out the region into the wide plain we see today.

A particularly good place to see the crater expanse is the Daniel, the steeple of the aforementioned St. Georg’s Church. From a height of 80 metres you can see in all directions the flat, fertile countryside with the hills forming the outer crater in the far distance.

A smaller meteorite simultaneously hit the region of Steinheim am Albuch, 40km away from Nordlingen. While the resulting crater was much smaller – just 3km in diameter – a distinct central uplift remains. Steinheim is a village well worth visiting. There is an excellent little museum in the hamlet of Sontheim im Stubenthal and plenty of well marked trails with wonderful views of the crater.

Addresses

Nordlingen:

Rieskrater Museum

Hintere Gerbergasse 3
86720 Nördlingen, Deutschland
09081 273822-0

http://www.rieskratermuseum.de/

Steinheim

Meteorkratermuseum

Hochfeldweg 5

89555 Steinheim, Deutschland

http://www.steinheim-am-albuch.de/meteor/

Advertisement

Lake Constance – Lindau and Bregenz

Lake Constance lies at the far southern tip of Germany. It is one of Europe’s “great lakes”, a major stopping point for the Rhine river as it meanders its way from the Alpine peaks to the North Sea. We started our trip today in Lindau, a pretty island town on the north-eastern shore of the lake. From there it was a short boat journey to the city of Bregenz in Austria. We took a cable car to Pfander – a mountain that provided some wonderful views of the entire lake.

Short video below:

Trip to Hochgrat, Bavaria

Hochgrat is a mountain in Bavaria, 1800 metres high. A cable car takes you to a restaurant close to the summit. The summit itself is a short scramble away. As well as the cable car, the mountain is accessible via a number of well defined walking routes. It was my first encounter with the Alpine Chough, a bird related to our own red-beaked sea crow.

Ulm Cathedral

Yesterday I visited Ulm Cathedral in Germany. At 568 ft high, its steeple is the tallest in the world. The sense of space inside the building is quite breathtaking, and the view from the top is, well, you’ll have to judge for yourself how well I coped with it..

Journey’s end..

I’m finally back from my world travels, having flown a distance of 18,000 km in the past ten days. My travels took me to Texas and Germany with a short stop in London. It’s been quite an experience. I have learned many things, such as:

1) To be very careful when booking flights with British Airways. If you try to change your booking within 24 hours of travel (even if the reason is legitimate, such as a freakin’ snowstorm), they will do everything in their power to stonewall you. I arrived in at 7.30 am into Heathrow and when I tried to get an earlier flight to Stuttgart than the 18.45 flight I was booked on, I was met with indifferent shrugs, middle-distance stares and a definite feeling that I was the bad guy for even daring to ask. I was happy to travel on standby, but that option was shut down straight away. I’m pretty certain that neither of the two earlier flights to Stuttgart that Saturday left with a full complement of passengers, but how could that possibly be their problem? That would be penetrating the bureaucracy, now, wouldn’t it?

2) Texans (at least the ones I met) are mindbogglingly polite and helpful. You could go nowhere without a “Can I help you?” or an “I beg your pardon” coming from somewhere. I have to put in a special mention to the American Airlines ground staff in Austin, who worked from 4 am to 7 pm on Thursday to ensure that all their passengers were taken care of. Almost every flight to Dallas had been cancelled and stress levels were stratospheric, but nevertheless these people worked wonders while keeping their sense of humour intact.

3) German people speak to each other in lifts, even if they don’t know each other. Now that’s just plain weird. Elevators are designed to make you feel enormously self-conscious and inadequate. This talking thing just isn’t playing by the rules.

4) When flying there is only one true currency: access to an electric power outlet. The more gadgets we carry around, the fewer chances we have to recharge. Methinks books are very safe.

5) I can now sleep on transatlantic flights! Actually, I can sleep on all sorts of flights! All they need to do is turn on the engines and pfffft, I’m out. This can mean only one thing. I’m getting OLD.

International Jet-Setter

This morning, at an ungodly hour, I am heading out to the airport to fly to Austin, Texas. I’m excited about it, despite the fact that it’s a work trip and I will be busy in meetings and other work activities for most of my time over there.

Although I have been to the US on dozens of occasions, I have never been to Texas, or anywhere near it. It’s a place that fascinates me no end. Maybe it’s the size of the state, or it’s natural beauty, or the unique personality of it’s inhabitants, I’m not sure. Austin is meant to be a particularly nice city, so I travel full of anticipation.

The journey itself is lo-ong. First of all London, then Chicago, then Austin, which means I will be spending most of the next 24 hours in planes and airports. I will be thoroughly wrecked by the time I arrive in the Lone Star state.

Following my trip to Texas, I head over to Stuttgart for a few days. I hope to visit the site of a huge ancient meteorite impact while there, as well as a small amount of skiing, perhaps. I’ve even discovered a pub there, (Biddy Early’s) that will be showing the Ireland vs France match next week.

So it’s all very busy and international and fascinating over the coming days. Hopefully I’ll have a few updates to share.

Catch y’all later.

Two and three decades on..

Photo: GothPhil (Flickr - cc licensed)

Today marks the twentieth anniversary of the fall of the Berlin Wall, an event I remember as if it were yesterday. The fall of the Berlin Wall was the high point of an astonishing period in world history, beginning with the fall of the Polish government in June 1989 and culminating in the collapse of the Soviet Union in 1991. In the space of a few months, the world changed utterly. The message, at least for a while, was one of hope: that repressive regimes can come to an end when the conditions are right.

Ten years before this, another political change took place in Iran, when the Ayatollah Khomeini wrested power from the Shah in a popular uprising that swept the nation. Khomeini created an Islamic Republic, supposedly freeing the country from the yoke of dictatorship and setting up a kind of utopia on Earth along Islamic principles. This new Iranian state quickly revealed itself to be just another tawdry dictatorship in clerical disguise, and now the youth of Iran are fighting for the same freedoms as their parents, thirty years ago.  Some are paying with their lives.

Photo: faramarz (Flickr - cc licensed)

If history is any guide, rotten regimes often  succumb eventually to a combination of relentless external and internal pressures. These pressures do not need to be violent, but they do need to be sustained. We can only hope that this will be soon be the fate of the current Iranian republic.

A weekend in southern Germany

I’m just back from a trip to Germany. I started in Munich, proceeded to Stuttgart and ended up in Wiesbaden.

A couple of random things from my trip:

In all the flights I have made – and I have flown hundreds of times – I have never seen anybody freak out when the plane is taking off and landing. This unblemished run ended last Saturday, when the woman seated in front of me had a full-blown panic attack. As the plane took off, the poor woman started to hyperventilate, emitting regular eeping noises as we hit any bumps or turbulence. She let out a full blown scream at one stage when the plane encountered an air-pocket in the cloud layer. She relaxed completely once we reached cruising height, but as the plane began it’s final approach, all around her were treated to a repeat performance. It must be terrible for her, as such an atavistic fear is not easily remedied.  

The German train system is pretty unforgiving if you make the mistake of leaving a suitcase on board. I had only stepped out of the train at Munchen – Pasing, when it dawned on me that something was wrong. Too late. Doors had closed and my suitcase was happily on it’s way to the small village of Geltendorf, about 20 km away. Suffice it to say that my suitcase and I were eventually reunited and that I spent the rest of the day making up for that brief moment of forgetfulness.

I can add fossil hunting to my list of achievements. One of the high-points of the weekend was a trip to Holzmaden, where some fantastic Jurassic Period fossils have been discovered over the last century. There is an open quarry there and members of the public can extract their very own fossils from the bedrock. We collected a nice set of ammonites and belemnites, although how they are going to get from Germany to Ireland is anyone’s guess. 

Other highlights were a trip down the Rhine and a relaxing day in the beautiful city of Wiesbaden. The public park next to the casino in Wiesbaden is particularly attractive. I was also struck by the friendliness and helpfulness of all the people I encountered during my trip. It’s definitely worth a visit.