A Walk in the Woods

The New York Times Science News just posted a great video - it's a discussion on evolution between NY Times Jim Gorman and Niles Eldredge. Their discussion takes place partly in Central Park, and then in the American Museum of Natural History where Eldredge is the curator of the current Darwin exhibit. Link to the video by clicking on: A Walk in the Woods . Once you link to the NY Times video postings, just scroll down the video list to "A Walk in the Woods" and click on it - it will then load into your media player.

National Grid Coordinates?

NPR had a brief summary of the rationale for using national grid coordinates in mapping on their Weekend Edition, 2/25/06 - http://www.npr.org/templates/story/story.php?storyId=5233408 . The story was mainly focused on emergency/disaster events, and the problems encountered with everyone using either a different grid system or just still using street addresses. NOAA has a web site that further explains the national grid system - http://ngs.noaa.gov/TOOLS/usng.html . The NOAA site also posts interactive conversions and a conversion program for all of us who use other grid systems like UTM or lat/long. NOAA does say that although the national grid system can provide for whatever level of precision a user desires, we still may prefer to use the UTM format for applications requiring precision greater than 1 meter. Interesting...

Sequence Stratigraphy in Continental Rocks

Here is an abstract on the importance of paleosols in continental sequence stratigraphic applications that we've submitted to the AAPG meeting coming up for Billings, MT in June of 2006. It's just some thoughts on the initial delineation of sequences in continental rocks:

Sequence Stratigraphy and Paleosols in Continental Rocks – Examples from Cenozoic Deposits of the Great Plains and western USA

Cenozoic continental deposits of the Great Plains and western USA can be separated into large-scale sequences that are variously marked by extensive paleosol formation, irregular topography developed on erosional surfaces, and/or angular discordance of strata. Abrupt changes in provenance or lithologies also may indicate a sequence boundary. Specifically, the interregional unconformities that bound these sequences within the Great Plains and western USA occur at about 55 Ma, 37 Ma, 30 Ma, 20 Ma, and 4 Ma. Hiatuses between sequences are variable in duration and can extend for several million years.

Paleosols are one of the more obvious sequence boundary markers. Because paleosols in many stages of formation may exist within a sequence, it is the advanced stages and pedocomplexes of paleosols that we use for identifying sequence-bounding surfaces. Calcic pedocomplexes are particularly useful in areas of arid to semi-arid climatic regimes, and in fact delineate four of the five large-scale sequences identified throughout the Great Plains and much of the western USA. The calcic pedocomplexes are readily identifiable on the surface with a pedocomplex typically being several tens of feet thick and containing several partial soil profiles. In the most complete scenario, an individual profile may contain an argillic or argillic/calcareous (Bt or Btk) horizon, a K horizon, and a C horizon. The calcic pedocomplexes also possess distinct physical properties that aid in subsurface identification. The combined density and velocity differences between paleosols and non-pedogenic strata result in bright reflections on seismic sections and distinct well log signatures.

Musings on a Winter Day

I'm just wondering about the usefulness of the online course concept for intro geology courses. After having written content for an 8th-9th grade level course, I'm left with the thought that geology is an observational science - at least for intro content. It would be interesting to compare what is taken from the course by kids that have done only an online course in geology with those that have taken a comparable course strictly in the classroom.