QUOTE (aldo12xu @ Jan 24 2006, 05:59 AM)
Man, it's amazing how much progress Spirit has made in such a short time. Nice panoramas, jvandriel.
Bill, Rock #4 looks like vesicular basalt, similar to what was seen on the Gusev plains, such as this:http://www.marsgeo.com/Photos/Spirit/Layer...icles128Lze.jpg
How smooth and featureless does a rock have to be before a "vesicular basalt" becomes a "non-vesicular basalt'? Or does the latter not exist? (I'm not a geologist, so I don't know.)
This classification exercise is quintessentially scientific, and I wouldn't be a scientist if I didn't encourage it. As a biologist I am
familiar with the problems of classifying animals and plants. We call the exercise systematics or taxonomy. When I have had to try the exercise with my own animals, I have suffered from a tendency to be a "lumper" rather than a "splitter". That is I tend to see continua
rather than discrete taxa or species or demes or what-have-you. How confident are you geologists out there that your 3 or 4 rock types
are discrete and not 1 or 2 continua
? I can see that a breccia (whether impact or volcanic) has a unique event in its genesis to separate it from other igneous rocks. Can the other types of basalt we are seeing be separated with similar confidence?
Thank you for trying to enlighten me.