Join us February 28 through March 1, 2019 at the Mapping Grand Canyon conference at ASU!
Geotechnical Special Presentation
Arizona Chapters for the Geo-Institute and Association of Engineering and Environmental Geologists Presents:
BRIDGE SCOUR AND ITS COUNTERMEASURES: MONITORING, STREAMLINING AND BIOCEMENTATION
Speaker: Julian Tao, Ph.D,
Associate Professor at Arizona State University
Date: Wednesday, September 19, 2018 — 5:30 p.m – 8:00 p.m.
Location: McFate Brewing Company 1312 North Scottsdale Road Scottsdale, Arizona 85257
$30.00 Members and Non-Members; $15.00 Government Employees and retirees; $10.00 Students Please RSVP by Monday, September 17, 2018
There may be some flaws from a deleted post that has the incorrect date. The correct date for the next dinner meeting is on Thursday, January 18, 2018.
August 16, 2017 at McFate Brewing Company
Speaker: Kelin Whipple, ASU, SESE
Topic: Interpreting Active Tectonics from Topography
Sponsored by: Tensar International Corporation
Landform analysis has become a standard tool in neotectonic studies. The timescales recorded in deformed landforms importantly bridge the gap between geodetic and geologic methods. Most commonly the offset, tilting, and warping of abandoned depositional landforms is used to infer deformation rates and patterns. Whereas such analyses of static landforms has become well developed, complementary approaches to extract quantitative information about tectonics from erosional landscapes are relatively new, rapidly evolving, and can provide powerful insight. Over the last couple decades, some useful general rules about the expression of rock uplift rate in erosional landscapes have been developed that can guide and augment studies of the spatial and temporal distribution of active rock uplift. At catchment scale, the relationship between landscape form and rock uplift is dictated largely by the response of stream profiles to rock uplift, which is largely one of changing channel steepness (gradient adjusted for drainage area). Changes in channel steepness along a stream can be either abrupt (discrete slope-break knickpoints) or gradual (expressed as zones of enhanced or reduced river profile concavity) depending on the deformation pattern. Landforms can record information about both spatial and temporal patterns in rock uplift rate. Landscapes in various parts of the Himalaya exemplify both spatial and temporal influences. I first highlight lessons learned about the relationships among topography, climate, and erosion rates from studies using cosmogenic isotopic concentrations in river sands over the last decade that importantly guide tectonic interpretation of landscapes. Then I illustrate application of these methods to three sectors of the Himalaya-Tibetan orogenic system: (1) the NW Himalaya in Pakistan (location of the 2005 Kashmir (Muzaffarabad earthquake), (2) the Longmenshan on the eastern margin of the Tibetan Plateau (location of the 2008 Sichuan earthquake), and (3) the central Himalaya in Nepal (location of the 2015 Gorkha earthquake). I show that both the 2005 Kashmir EQ and the 2008 Sichuan EQ occurred on steep out-of-sequence thrusts in events predicable from the topography. The central Nepal location is interesting in that the topography indicates a similar architecture of active faults, but the long-expected 2015 Gorkha EQ ruptured the gently dipping basal decollement and not the inferred steep out-of-sequence fault. I explore the implications of the 2015 Gorkha EQ, and controversy around interpretations of structural architecture, in some depth.
The use of basalt in food preparation and art in prehistoric contexts was worldwide. Sourcing, selection and if needed the forming of the basalt was largely dependent on the intended use.
In both food preparation and art there was overlap in the rock type available and chosen, as it ranged from vesicular to smooth, from horizontal bedrock to sheer vertical face and from the labor of quarrying to a short stroll for a large rock canvas. This presentation will take focused looks at two different types of basalt applied to two different human needs.
Speaker: John D. Rockhill
John D. Rockhill is an archaeologist with Amec Foster Wheeler in Phoenix, Arizona with 20 years of field and laboratory experience in the southwestern United States, Egypt and Sudan. John was born and raised in Safford, Arizona and received his Bachelor of Science degree in Biology in 1975 from the U.S. Air Force Institute through the University of South Carolina. John has worked on and directed a number of field projects with emphasis on large scale survey, mapping and excavation of prehistoric and historic sites and their features and the laboratory analysis of lithic, glass and metal artifacts.