Tuesday, March 24, 2009

Regime change

I was able to spend time in one of my favorite places in Utah, Cedar Mesa also known as the monument uplift. This area is directly south of Canyonlands NP and much of the southern drainage from the Abajo Mountains comes this way. The soft Cedar Mesa sandstone has eroded into a set of incredible canyons from this drainage. What makes this doubly fun is the amount of Anazasi (Ancestral Puebloan) ruins and rock art found throughout the canyons.

The upper elevations of the mesa tops is known as the Red House cliffs. The base of the cliffs are made of the Permian Organ Rock shale while the mesa top is capped with Triassic Moenkopi and Chinle formations. These red beds indicate bright oxidized muds from the Ancestral Uncompaghre uplift to the east. The drainage at the time making large alluvial fans that filled this part of Utah.

Below the red beds of the Organ Rock/Moenkopi/Chinle lies my second favorite rock unit on the Plateau: Cedar Mesa sandstone. Being as this is the type area, the Cedar Mesa sandstone makes up the majority of Cedar Mesa. Almost every canyon is cut into this very thick white Permian sandstone. The sandstone shows obvious large scale crossbeds and a uniform grain size suggesting wind blown deposits. You can see the crossbedding in the space below the granary. I have read a petroleum description that this is a wet eolian deposit. This is in keeping with the idea of a cyclic rising and falling of local sea level.

Under the Cedar Mesa is the Elephant Hill Limestone . This is one of those limestones I enjoyed using as a prop in intro geology labs. Its a sandy limestone more than a limy sandstone. There are fossils present and samples will do all the things limestone should do in field tests.

So for about 80 million years you can see regime changes happening; seas coming and going all the time. Now this area is  very arid region. If the regime was different, lets say similar to the East coast, so much of the existing rock would have eroded away and these magnificent canyons would be nothing but a flat plain.

Tuesday, March 17, 2009

The newest crop of Earth Scientists

I had the opportunity to be a substitute teacher yesterday for a local 5th grade class. While there we did the usual elementary school daily events: math, writing, recess, reading and spelling. Unfortunately I was not to be the science teacher, but I quickly made the math class into an hour filled data collecting exercise and study of probability.  It was at lunch when I was looking at the stuff all around the room and noticed a wall full of astronomical posters. One poster highlighted variable stars. I thought that was an unlikely topic for a 5th grader to study. I asked the other teacher about the choice of variable stars. I wasn't expecting her answer. The girl who studied variable stars choose the topic because the picture in the book showed a pink star.

I am sorry to say my first reaction was very guy-like with a laugh (to the teacher not the student!). But, I quickly started wondering. Do we create our elementary science posters/text/web pages etc. To attract both genders? I don't know? I think that the newest images coming from the Hubble are beautiful works of art. I am reminded of Jodie Foster in Contact saying that they should have sent a poet. But, I am a guy. What do these images look like to 5th grade girls? And what do you think about creating more pink stars to find the next Vera Rubin, Jill Tarter or Annie Cannon.

Friday, March 13, 2009

writing and more writing

Last fall I was offered a contract to create a new middle school online earth science course. I was slowly working my through their outline and keeping up with all the small yet numerous editing changes.  Three weeks ago I was told that I really needed to be finished by the end of the next budget cycle...you know what that means.  I'm an independent contractor so I am not employed anyway but I wanted the money. My deadline is this next Monday morning. 
So three weeks of writing, editing rewriting with 6th grader readability (just watch I'll be writing simple sentences for the next few months).  I have been finding just the right image, working on remote servers, having MS word crash just a few times and trying hard to require some inquiry in the lessons. I am tired and as of about 1 hour ago, finished! I beat the deadline. Now the first set of editing takes place but first some serious time outside all next week

Tuesday, March 10, 2009

Winter returns

After yesterday's post...we wake up to 4 inches of heavy wet snow. The moisture is needed, it always is! What a difference though.

Monday, March 9, 2009

Thursday, March 5, 2009

1.5 billion year view

Last weekend's lunch spot was on an easy scramble to near the top of the Wingate formation (my favorite!) The Wingate is a superb homogeneous sandstone early Jurassic in age. Directly below the Wingate in all that red stuff you can see between my feet is the Chinle, famous for its Uranium mines found all over the Colorado Plateau. The Chinle is Triassic in age. It is difficult to see, but in the upper right of the picture are some darker rocks. These black rocks are Proterozoic in age, about 1.8 billion years old, if my research is right. There appears to be a bit of time missing, like the entire Paleozoic. 

If we round and say that the top of the Wingate was deposited 200 million years ago and that the Black rocks were placed about 1.8 billion years ago, then the view from top to bottom takes in a little more than 1.5 billion years, a full quarter of all of the history of the planet. Cool!