Way cool - first of the season - sounds great when you haven't heard it in probably 9 months. :) It's raining - ooo, more thunder! Cool! Now it is hailing - aside from the damage/injury factor, hail is really neat - it bounces on the ground when it hits and looks like snow sometimes after it is all over. Ahh, there go the warning sirens - but the weather has already moved on - no tornadoes here.
Grand Canyon Lava Flows
The above link is to a neat image that shows the lava flows that used to cascade down the sides of the Grand Canyon and dam the Colorado River. Can you envision that? It must've been quite a sight! Click on the high resolution image after the description - it looks much better.
I often think about geologic processes and time. I have this little fantasy of being able to see all the changes that have happened on Earth, see where people have been and what they did, and see all the animals that ever lived, etc.
For example, yesterday I was watching some NOVA reruns (one of the best TV shows ever, folks) and one of them was about a place up north called the Scablands. It turns out that during the past glaciation period, glaciers came down into Montana and blocked a river creating a lake called Lake Missoula - it was a huge lake, like one of the Great Lakes of today, and modern day Missoula would've been nearly 2000 feet under water at that time. Well, water gets into the cracks of the ice and eventually causes the ice dam to break, like what happened in Iceland in '96. When this happened, it created a massive, fast and powerful flood-draining of the lake all the way into Washington and to sea. The water flow of the draining created potholes in the scablands tens of feet wide and deep - features that exist nowhere else on Earth. What's more, it happened over and over again perhaps hundreds of times. It is possible people might have witnessed it or even been victim to it - who knows?
And then I was watching a Deep Sea Detectives rerun and they were investigating cenotes in the Yucatan and Cozumel Island. These are pools of water that Mayans held as sacred entrances to the underworld and would drop sacrificial items (and apparently people) into them. In this episode, the divers were diving in from an entrance at the coast into the caves for more than a mile to get to a deposit of offerings that had been discovered with no apparent above-ground entrance that they could've been deposited from. First thing that was awesome was seeing the halocline - the boundary between the salt water and sea water - that they passed through. Then, seeing these caves that are now underwater but were completely formed above water. Caves take a long time to form and they form on land, not in sea, but now they are covered. So I wonder, how long ago were they above the water? My guess is that it was during the last Ice Age, because sea levels were lower then. Did anyone ever see them above ground? Similarly, there are people who think the Bimini Road is manmade. I don't know that it is, but there is increasing evidence of a lot of archaeology to be done underwater - evidence of human habitation in places now underwater. It is all fascinating to me!