Frank Groffie, PG, CEG                  Geology consulting                      Clarity, communication, closure.                             Contact us ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
About   Fault investigation   Landslide investigation   Rock-slope analysis   Seismic hazard analysis   Site characterization   General geosupport	Geologic site characterization  The basic geologic character of a site is important. Get it right. Use sedimentology to correctly identify core samples as Pleistocene alluvium rather than Jurassic volcanic bedrock. Use sedimentology to spot overturned bedding and distinguish artificial fill from natural deposits. Measure bedding attitudes only when you’re measuring true bedding rather than other features. Use, but recognize the limitations of, available geologic maps. Use aerial photos to distinguish between landslide terrain and stable ground. Use photos and principles of neotectonics to focus on true candidate fault traces rather than faint lineups of random features at the limits of human visual perception, i.e., know the limitations of aerial photos. Recognize paleosols, terrace deposits, and soil horizons in exposures.  Frank Grofffie has practiced these and other basic geologic strategies to avoid geologic errors by others, and to  otherwise generate valuable accurate geologic data for development projects. Below are a few examples.
	Las Palmas Ranch, Monterey County  ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯  This 1,433-acre residential site is situated between  the Salinas River and State Route 68.  By a blend of much boot-leather wear, university  library research, and reviewing published geologic  maps, Frank Groffie1 developed a reinterpreted,  accurate geologic characterization of this site and  helped residential development proceed. He identi-  fied multiple sets of isolated stream terrace depo-  sits stranded at high elevations. His recognition of  an important Pleistocene paleosol led to a complete  reinterpretation of bedding orientations. Formerly  “stable” slopes were reinterpreted as unstable and vice versa.  He recognized that a sewage treatment plant under construction was threatened by an active landslide and  helped observe the rescue of the plant while the landslide moved. The issue of a Rinconada fault (judged  inactive) was also investigated.
	Large ranges of geologic complexity  ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯  Pristine sites, even large ones, can be relatively easy to characterize. Still, there may be conditions that make  for interesting geologic puzzles. At one such site, bedrock was Tassajara Formation that has been uplifted and  tilted a remarkable degree considering its deposition only a few million years ago. Close examination of subtle  sedimentologic features in test pits and thorough office analysis by Groffie allowed a jumble of seemingly com-  plex bedding dips to resolve into a simple model of broad folding and overturning caused by a “blind” thrust  fault.  Quarried sites, small or large, may have a unique set of issues. Work with air photos and backhoe exploration  becomes critical, and seismic-refraction surveys become useful in the hunt for random loose quarry deposits.  When the bedrock geology also includes Jurassic oceanic basalt, conglomerate, and shale in either depositional  contact or ancient subduction zone shear juxtaposition, and colluvium and a Hayward fault trace are thrown  into the mix, then one is dealing with a site with a good degree of geologic complexity.
	Landslide, Oakland  ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯  A steep hillside in Oakland slid onto a city roadway about twelve  years ago. Residential properties at the top and right in the photo  were affected.  In 2000, Frank Groffie2 investigated the site using published maps,  aerial photos, and several drill cores and inclinometer installations. He  prepared a draft document reporting that the landslide was new (not  preexisting), had formed within a unit of Pleistocene alluvium, includ-  ing beds of well-sorted stream sands with rounded pebbles, and could  be characterized by slide planes found at moderate depths in oriented  cores and inclinometer offsets.  Others prepared earlier and later reports with erroneous interpreta-  tions. For example, well-sorted stream sands were excluded from core  logs, and other geologists incorrectly identified the subsurface as  Jurassic rhyolite bedrock.  Much later, geoscientists from Gilpin Geosciences performed defini-  tive, large-diameter site exploration. They prepared a report that  validated all of Groffie’s original interpretations. The recent photo  shows the landslide repaired.
	Ranch, potential residential site, Monterey County  ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯  We investigated the geology of this ranch  in Monterey County, California.  Frank Groffie2 concluded that a potentially  active thrust fault may lie along topo-  graphic inflection points at the bases of  the faceted ridge spurs, based on neotec-  tonic and paleoseismologic principles.  Other geologists, including one (former)  associate, believed that (1) topographic  saddles between bedrock knobs and (2)  faint tree alignments across the lower-  elevation grass fields all equal fault traces.  Hundreds of feet of trench logging work by  Groffie showed no fault traces. Despite  misdirection by others, Groffie was able to  document feasible building sites among  stable granitic geology and relict stream terrace deposits, along with areas of debris-flow deposits and recent  debris flows, where mitigation might be necessary for future residential building sites.
	Homesite, Contra Costa County  ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯  This property is the site of a large, older home in Contra  Costa County that enjoys spectacular views of the Bay  Area, though it’s often shrouded in mist as in the photo. It  sits at the top of a knoll at an elevation of 600 feet.  Groffie performed an investigation3 that included 170 feet  of trenches. Guided by past collaborations with Dr. John  Wakabayashi, he logged two zones of basalt sandwiching a  slab of serpentinite. The two main shears between these  three principal rock slabs dip to the northeast, into the  hillside, in agreement with typical rock relationships and  structure he has observed numerous times in the East Bay  hills. Groffie, guided by past collaborations with Dr. Glenn  Borchardt, logged several soil horizons, some Pleistocene in age, all of which are developed without offset over  the tops of the shears. Groffie gave approval to a zone of potential future homesite construction. A peer  reviewer observed the trench exposures and agreed with Groffie’s interpretations.4
	Publications  ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ Your Geologic Services A 9-page tutorial describing what we geologists do for our clients. Written in simple, plain language and with 16 useful color illustrations.                                                                                                            Frank Groffie's Miscellany A few web pages presenting publications and comments on various topics ranging from serious to fun.
	1. As employee of Terratech, Inc., client legal relationship with that firm, since absorbed into other corporate entities. Relevant      technical documents on file as public record with applicable public agencies.   2. As employee of Harza Engineering Company, Inc., client legal relationship with that firm, since absorbed into other corporate      entities. Relevant technical documents may or may not be on file as public record with applicable public agencies.   3. Relevant technical documents on file as public record with applicable public agencies.   4. Another report, on file as public record with applicable public agencies, exists for the same site. Trench logs show colors pro-      duced by localized gleying (present but not recognized as such) used to produce a log with all sorts of incompatibable rock      types (not present). Large slabs of serpentinite were erroneously logged as basalt, and vice versa. No soil horizons were      identified. One of many tiny illusory top-of-bedrock irregularities was logged as an active fault trace passing across a hilltop,      with a trend 50 degrees off the main trend of the Hayward fault, with a purported normal-fault sense of displacement (perhaps      some atypical form of antithetic faulting in a compressional environment?), counter to local mountain-forming processes that      should display a thrust style of displacement.
Frank Groffie, PG, CEG, MSc, is Professional Geologist 4930 and Certified Engineering Geologist 1539, in good standing since initiation in 1989, with the State of California Board of Professional Engineers, Land Surveyors, and Geologists    Web page last modified January 29, 2013.