Friday, February 25, 2011

Your Mars Lesson of the Week

Posted By on Fri, Feb 25, 2011 at 4:45 PM

The UA Lunar and Planetary Lab's Alfred McEwen talks about a HiRISE photo from Mars:

Some of the largest landslides known in the Solar System have happened on Mars. These are interesting phenomena, but they also sometimes produce excellent exposures of the bedrock geology, in cross-sectional views. The purpose of this image was to view bedrock exposures at a deep level in Valles Marineris.

We have only a vague idea how old these rocks are. Crater counts date landscapes, and clearly this is a young landscape with very few impact craters due to the continual mass wasting (landslides) of the steep slopes. The rocks are much older—probably older than the plateaus surrounding Valles Marineris (2 to 3 billion years based on the large craters), unless these are intrusive rocks emplaced later from migrating magma. We need radiometric age dating, either on Mars or from returned samples, to measure the age of igneous (volcanic or plutonic) rock layers within the strata.

The age of sedimentary layers such as river or lake deposits can be bracketed by the ages of overlying and underlying igneous layers. Not knowing the absolute ages of bedrock units on Mars is a huge limitation to our understanding of the geologic history.

Lots more here.

Comments

Subscribe to this thread:

Add a comment

More by Jim Nintzel

Today | Thu | Fri | Sat | Sun | Mon | Tue
Burlesque Fitness

Burlesque Fitness @ Floor Polish

Mondays, Wednesdays, 4:30-5:30 p.m.

All of today's events | Staff Picks

Staff Pick

Carnival of Illusion: Magic, Mystery & Oooh La La!

This top-rated illusion show is "Revitalizing Magic" by blending an international travel theme with all the charms… More

@ Scottish Rite Grand Parlour Saturdays. Continues through April 14 160 South Scott Ave

» More Picks

Submit an Event Listing

Popular Content

  1. Cutting Teacher Compensation and School Funding in Wisconsin (The Range: The Tucson Weekly's Daily Dispatch)
  2. Laughing Stock: The People's Pervert Does Christmas (The Range: The Tucson Weekly's Daily Dispatch)
  3. UPDATE: Please stop sending your sweet, sweet turkeys! (The Range: The Tucson Weekly's Daily Dispatch)
  4. The 'Freedom Center's' High School Course Is On Shaky Ground at TUSD (The Range: The Tucson Weekly's Daily Dispatch)
  5. Steve Bannon Beats the Drum Against Undocumented Immigrants in Tucson Appearance (The Range: The Tucson Weekly's Daily Dispatch)

© 2017 Tucson Weekly | 7225 Mona Lisa Rd. Ste. 125, Tucson AZ 85741 | (520) 797-4384 | Powered by Foundation