Bimrocks

Franciscan melange in Headland at McKerricher State Park nr Fort Bragg Mendocino Co (E Medley)

Stopped by because you are looking for information on bimrocks? Then go to my bimrocks website for the current collection of resources on bimrocks for geological and geotechnical practitioners.

What are bimrocks? Bimrocks are block-in-matrix rocks, mixtures of stronger blocks of rock surrounded by weaker matrix rocks. Bimrocks are geologically, spatially, and mechanically heterogeneous. Bimrocks include melanges, fault rocks, weathered rocks, lahars and some “rock/soil mixtures.”

So What? Bimrocks universally frustrate the economic and accurate characterization, design and construction of civil engineering works.

Who cares? Bimrocks are troublesome to geotechnical engineers, geologists, contractors and owners.

Isn’t bimrocks a silly word? It looks silly, sure.  Nevertheless, it is a serious geological engineering term.  I coined the geologically neutral word bimrocks to focus engineers’ attentions on the fundamental and troublesome fabric of strong rock blocks in weak rock matrix, regardless of geological origins and euphonious geological names. Geology is important, but engineers generally do not understand the rich language of geology and are confused by (and even dismissive of) geological words.

Aren’t bimrocks rare? No, they are very common. So there is no excuse to ignore them.  I don’t: I live and work near San Francisco, which hosts the Franciscan Complex (“the Franciscan” for short), a regional-scale jumble of shards of earth’s crust, interspersed with some of the most spectacular melanges and bimrocks in the world. I have written some on such rocks, but others write far more: there are thousands of papers on melanges, a good proportion focused on those of the Franciscan.  If you are interested in San Francisco area bimrocks, then look at this 2018 Field Trip Guide

For some overall guidance to bimrocks see the Introduction and Summary Lectures for the Short Course taught in 2017 at Medellín, Colombia (Lecture PDFs can be downloaded); or, the annotated  but clunky-looking  “Introduction to Bimrocks”, Also useful may be the 2011 paper: Geopractitioner Approaches to Working With Anti-Social Melanges, a chapter in the book Special Paper 480: Mélanges: Processes of Formation and Societal Significance, by John Wakabayashi and Yildirim Dilek, published by the Geological Society of America.