Abstract: 

More than 90% of the 2400 km2 catchment area of the actively uplifting San Gabriel Mountains (SGM) drains southward towards Los Angeles, the second largest metropolitan area in the United States, through an extensive reservoir and flood control system. In terms of downstream effects, the SGM is arguably one of the most important mountain ranges in the United States. The prevailing view is that short-return fire-flood-debris flow cycles dominate denudation of the SGM, however, emerging research suggests the role of bedrock landslides is likely significantly underappreciated. This talk will highlight (1) geochronology results that demonstrate that some of the largest landslides in the SGM formerly thought to be Early Quaternary in age (1-2.5 Ma) occurred during the Late Holocene, (2) a bedrock landslide inventory of the SGM with over 11,000 landslide deposits that significantly increases their known abundance, and (3) case studies of major landscape effects including 150m vertical aggradation pulses and drainage reorganizations driven by landslides. This new perspective has important implications for the Los Angeles region, particularly if many of these landslides are coseismically triggered. To our knowledge the SGM landslide inventory (LSI) is the only systematic, range-scale, lidar-resolution inventory of its kind in the world to date; the talk will also cover some of the novel techniques employed to produce this LSI, example spatial analyses it enables, and ongoing efforts to have the database incorporated into the California Geological Survey’s statewide LSI.

Abstract: 

This talk will highlight the key activities that a geologist provides on a large dam re-construction project. The majority of the talk is about how a small group of geologist used drill penetration rates to model the site geology and predict the quality of rock to more effectively blast and develop the Emergency Spillway quarry at the Lake Isabella reconstruction project. Conclusion – You can use drill penetration rates to characterize the geologic conditions at a site.

Abstract: 

Throughout much of California, the Miocene Monterey Formation appears excessively deformed compared to other spatially or stratigraphically associated rock units. Whether it was syn-sedimentary vs. post-depositional tectonic deformation has led to many stimulating arguments in the field. Some of the deformation is clearly the a mechanical result of its heterogeneous, thin-bedded character that permits complicated flexural-slip folding. However, much of the complexity arose from the rapidly changing tectonic setting during and following deposition over the past ~10 Myr. Spectacular beach platform and cliff exposures between Crystal Cove State Park and Corona del Mar, California, were studied by the 2020 CSULB Field Geology class to unravel this complex history. The intrepid students braved tides and waves to make many 1000’s of measurements of open and tight folds, primary and secondary fracture sets, deformation bands, instrastratal microfaults, and multi-layer cross-cutting thrust faults, normal faults and conjugate fault sets in Monterey dolomite, mudstone, chert and sandstone. We identified a succession of deformational events that partly meshes with the previously published regional sequence of extension, rotation and transpression, but also differs in some ways – likely due to the basin-margin setting between the Newport-Inglewood and Pelican Hill fault zones. Be prepared to immerse yourself in many beautiful photos of the complicated geology and an abundance of stereonets to understand the spatial and temporal relationships that unfolded.

Abstract: 

Josh Goodwin, from the State Board, will present valuable information to assist geologists applying for their licenses (GIT, PG, CEG, CHG, PGp). Mr. Goodwin will also assist current licensees by explaining common pitfalls that can result in lost licenses, and how to avoid those pitfalls.

Abstract: 

Drones equipped with diverse payloads, such as high-resolution RGB cameras, thermal and gas detection sensors, and LiDAR, are transforming geotechnical and environmental work, landscape design, and surveying. These technologies enable rapid acquisition of high-resolution and accurate spatial data while significantly improving personnel safety. Drone imagery, including photos and 4K videos, supports detailed site monitoring and environmental assessments. When drone images are processed photogrammetrically, data outputs like orthomosaics, digital terrain and surface models, 3D meshes, and point clouds can provide precise high-resolution (cm-scale) georeferenced topographic information and facilitate site monitoring and assessments, infrastructure and sample location mapping, and area or volumetric calculations. Additionally, drone-derived models are utilized for slope stability and erosion change-detection analysis and monitoring. The integration of drone data within industry workflows enhances decision-making, reduces costs and fieldwork duration, and improves the quality and safety of site assessments across small and large projects.

Abstract: 

The dynamics and deformation history of the Eastern California Shear Zone (ECSZ), a wide and complex network of right-lateral strike-slip faults within the Mojave Desert, is not well understood, despite hosting three large earthquake ruptures in recent decades. The low-net slip faults of the ECSZ (<10 km each) offer a unique opportunity to assess the strain distribution and kinematic evolution of a developing strike-slip system. To do so, we conduct investigations of 1) the morphology, structure, and potential growth of numerous small (kilometer-scale) restraining bends along the southern ECSZ faults and 2) the slip rate of the Calico fault, the longest and fastest right-lateral fault of the ECSZ. We find that the majority of restraining bends studied are doubly fault-bound positive flower structures and their small size and shallow crustal penetration (<5 km) may make them unlikely to impede large earthquake surface ruptures. However, the bends may be growing with cumulative slip and our numerical deformational modeling results suggest that the secondary faults initiated as a mechanism to accommodate horizontal shortening as uplift between the faults. Next, we find a preferred Calico fault slip rate of 1.5 +0.9/-0.7 mm/yr since the late Pleistocene as determined from new mapping and geochronology of offset alluvial fans just north of Hidalgo Mountain. These rates are consistent with prior rates from the Rodman Mountains and together indicate a ~38 km long kinematically coherent fault segment with a relatively steady slip rate of 1.7 +0.4/-0.3 mm/yr over the last 60 ka. Slip rates from Newberry Springs, however, were previously found to be 2-3 times faster, implying either significant spatial or temporal variations. Determining spatiotemporal slip rate changes in other ECSZ faults may be critical to understanding regional strain rates, but insufficient geological fault data remains a major limitation.

Abstract: 

Conclusions will be presented for a local to regional seismic hazard evaluation for the Beverly Hills Unified School District (BHUSD) conducted by the author from 2011 to 2016. This study was primarily motivated for health and safety concerns due to the antiquity of many of the existing structures at various campuses in addition to METRO deciding to divert a proposed subway tunnel from Santa Monica BLVD to Constellation BLVD. The diversion placed the top of the proposed tunnel ~50-feet beneath Beverly Hills High School. BHUSD had valid concerns about a potential sinkhole during construction and future campus developments, some of which proposed to extend underground due to limited campus aerial extent.

Another seismic hazard arose for BHUSD from geologic-fault studies associated with the proposed METRO subway and their well-known retained paleoseismologist consultants. These studies proposed a previously unrecognized north-south trending fault zone associated with north-south trending geomorphic Cheviot Hills Lineament. They mapped the proposed Cheviot Hills fault zone through the entirety of the Beverly Hills High School campus. However, published geologic map and local stratigraphic and structural studies conducted by oil companies had long mapped the east-west trending Santa Monica fault zone in the vicinity of the northern portion of Beverly Hills High School. Thus, at the time of this study, there were two “published” orthogonal fault zones potentially intersecting in the Beverly Hills High School campus! An important regulatory aspect of evaluating seismic hazards at the time was that the California Geological Survey was actively working on creating AP-Zone fault hazard maps for the Santa Monica and Hollywood fault zones during the time. Thus, METRO geotechnical studies, the Kenney GeoScience study, and many fault investigations for many properties in the BHUSD vicinity occurred without the aid of regulatory fault hazard maps.

The Kenney GeoScience study involved evaluating local data to better understand the local stratigraphy and structure in the vicinity of BHUSD, and regional data across the entire northwestern Los Angeles basin that included offshore and onshore geologic publications. My presentation will provide a summary of findings that occur within the Beverly Hills High School campus, in the vicinity of the campus including the Cheviot Hills and western Hollywood basin, and more regionally focused on the east-west trending Santa Monica to Hollywood fault zones.

Abstract: 

As my home, it has always puzzled me by how unstudied Orange County really has been. Sure there are geologic maps, and we can see the geomorphology out there, but do we really understand it? And why not? Hence my decades (career) long effort to generate that understanding and communicate it to others as best I can. This was never a solitary effort, there are too many to name who have helped in many ways: trench scraping, field trips, discussions, suggestions, and sometimes laughter. To them I am deeply appreciative, but any errant conclusions within this talk are not their fault.

Orange County California is home to over 3 million people making it the sixth densest county in the U.S. From its high point atop Santiago Peak it is 5,689 ft (1,734 m) down to the coastline at Laguna Beach, a distance just shy of 100,000 feet (30,000 m). The San Juaquin Hills at (height) and Puente Hills at (height) bound the west and northern county. But at 3 Ma, none of this expensive real estate yet existed; Orange County was part of the Pacific Ocean. This talk will try to explain how this came to be, by starting the clock at 3 Ma and ticking our way up to today.

The Santa Ana Mountains are an indenter (think hydraulic piston) driving northwesterly at ~6 mm/yr by the Elsinore fault. As they close the basin, the entire Cretaceous – Pliocene sedimentary section is folded, faulted and piled onto the front of the indenter. Meanwhile the Puente Hills thrust forms in response to north-south compression against the San Gabriel Mountains. As the compression tightens by 1 Ma, other structures begin to emerge as transpressional folds and faults; the San Joaquin Hills and the Peralta Hills, while the Whittier fault accommodates about 3 mm/yr of right-lateral strain as the basin slides out to the west.

Today, the indenter is in full train-wreck mode as it completes the collision with the Puente Hills in Santa Ana Canyon. We can see this expressed in both the geology and geomorphology of the Canyon. As that collision has tightened, the uplift rate of the Puente Hills has tripled to ~3 mm/yr today. Today we see extensive landsliding in the Canyon area due to that jump in uplift rates for already crushed and seismically weakened Puente Formation rocks, as well as hundreds of small faults, fractures and folds any of which could be candidates to accommodate (minor) deformation in a future earthquake. Orange County is a happening place.

Abstract: 

New Mexico offers spectacular geology sites such as mesas, volcanic necks, arches, and gorges, but Paul, after presenting four regional geology features of the state, will focus on geologic sites unique to New Mexico including two subsurface atomic explosion experiments, a large magma body, an actively produced CO2 field, and special geology of the Permian Basin and its evaporites.

Abstract: 

Lithium: the hot metal everyone can’t get enough of. With the push for increased electrification, the world needs more electrical storage (batteries) requiring more and more lithium. Found all over the earth, lithium is ultimately derived from two geological sources: brines and hard rock pegmatites. Rarely forming in minerals, this metal is often concentrated only in the final stages of magmas. As our need for lithium grows, we will need to exploit new sources: some well known but uneconomical and some yet to be discovered. This talk will serve as an overview of the geology of lithium deposits while explaining why we find lithium where we do. We will also explore the global lithium market, the future the US and California may play in it, and how upcoming technologies may completely change how we approach lithium resources.

Abstract: 

This talk will provide a whirlwind tour of the Alpine Fault in New Zealand, often considered one of the world’s “big three” active continental strike-slip fault systems (alongside Turkey’s North Anatolian and the San Andreas). The fast slip rate (∼30 mm/yr), regular recurrence interval (249 ± 58 yr), and time of last earthquake (1717 CE) yield a 75% probability of Alpine Fault surface rupture in the next 50 years, making this one of the world’s most anticipated earthquakes and distinct national-level hazards. The race is on for scientists to learn what they can and communicate it into actionable policy and planning before this earthquake strikes. This talk will provide an overview of our state of knowledge, including the most spatiotemporally complete paleoearthquake record in the world and new lidar-revealed insights into earthquake displacements, slip rates, uplift rates, and landscape effects. A spotlight will be placed on a recent study that used curved scratches (slickenlines) on fault surfaces to constrain the rupture locations of past Alpine Fault earthquakes, demonstrating the utility of a brand new paleoseismological tool applicable to surface-rupturing faults globally.

Their research is largely conducted on federal lands administered by the National Park Service, including Tule Springs Fossil Beds National Monument, Death Valley National Park, Joshua Tree National Park, Channel Islands National Park, and the Mojave National Preserve.

In White Sands National Park, Kathleen and Jeff have combined their region-wide experience with detailed stratigraphic analyses and cutting-edge dating techniques with their intimate understanding of past climate events to establish the age, geologic context, and paleoenvironmental setting of ancient human footprints recently discovered there – including the link to abrupt climate change that allowed the human and megafaunal footprints and trackways to be created and preserved. Archaeologists and researchers in allied fields have long sought to understand human colonization of North America. Questions remained about when and how people migrated, where they originated, and how their arrival affected the established fauna and landscape. evidence from excavated surfaces in White Sands National Park (New Mexico, United States), where multiple in situ human footprints are stratigraphically constrained and bracketed by seed layers that yield calibrated radiocarbon ages between ~23 and 21 thousand years ago. This timing coincided with a Northern Hemispheric abrupt warming event, Dansgaard-Oeschger event 2, which drew down lake levels and allowed humans and megafauna to walk on newly exposed surfaces, creating tracks that became preserved in the geologic record. These findings confirm the presence of humans in North America during the Last Glacial Maximum, adding evidence to the antiquity of human colonization of the Americas and providing a temporal range extension for the coexistence of early inhabitants and Pleistocene megafauna. Independent chronologic controls have confirmed the ages are correct and is the subject of our ongoing research. These results have upended traditional models regarding the peopling of the Americas and fundamentally change the very foundation of North American archaeology.

Quaternary Hydroclimate Records of Spring Ecosystems | U.S. Geological Survey

Fossilized Footprints – White Sands National Park (U.S. National Park Service)

Article Link: Evidence of humans in North America during the Last Glacial Maximum | Science

Abstract: 

Permian-to-Cretaceous igneous rocks of the Sierra Nevada Mountains were generated by almost 180 million years of oceanic plate subduction beneath the western edge of the North American continent. Tomographic imaging of the mantle beneath the southern Sierra Nevada reveals the presence of multiple oceanic slabs that implicates a complex history of Mesozoic continental collision, slab break-off, and crustal extension. This talk will explore the Permian-through-Jurassic tectonic evolution of southwestern Laurentia by integrating four different aspects of zircon geochemistry with field-based geology.

Abstract: 

The Santa Monica fault zone (SMFZ) extends across much of the densely populated City of Beverly Hills in southern California. State and local agencies require that active (Holocene) splays of the SMFZ be located and avoided (structural setbacks) prior to new construction. Accordingly, based on interpretation of ~80-100 m deep continuous cores, on arrays of cone-penetrometer tests (CPT), on limited geophysical data, on local street trenching, and on downhole logging of up to 15-m deep, overlapping bucket-auger holes, the ~300-m wide SMFZ is now documented to impact at least several famous, multi-million-dollar commercial structures in the “heart” of the Beverly Hills business district (Rodeo Drive). Subsurface sediment correlation is typically deduced from interpretation of 3-m centered continuous cores and cone penetrometer test (CPT) soundings. Sediment age is preferably based on multiple radiocarbon or OSL (optically stimulated luminescence) dates; but, in the common absence of such, soil-stratigraphic dating techniques are generally used.

Vertical fault displacement of a few cm may not be recognized owing to lack of slickensides on near-surface sediments and to 0.5-1.0 m-deep local channel incision. Where logistically feasible trenches may be excavated beneath existing structures in order to expose and measure possible fault offset and sediment age. The depth to the local Pleistocene/Holocene boundary varies, but – based mainly on radiocarbon and soil-stratigraphic dating – locally occurs between ~ 6-8 m, typically too deep for urban trench exposure. Increasingly, therefore, consultants drill 20-30, overlapping, 0.8 m diameter bucket-auger holes, which, when cleaned and logged, emulate trench walls. Such drilling is particularly expensive in cities and is typically done at night to reduce disruption to traffic and commercial activities. Coupled with difficulties of locating and avoiding unmarked utility lines and with required State and City technical reviews and permits, investigating the possible presence and impact of active faults on a single Beverly Hills commercial building may take over a year and exceed a million dollars.

Key words: urban active faults; investigation techniques; Beverly Hills, California

Abstract: 

The Sierra Nevada has played an important role in the history of paleoglaciology in the United States, and indeed globally.  The role of glaciation in shaping the range was discussed by J.D. Whitney, John Muir, and Joseph LeConte in the late 1860’s and the 1870’s.  Even at this early time, the evidence was abundant that the Sierra Nevada had been extensively glaciated in the not-too-distant geological past.

When Elliot Blackwelder in 1931 provided the first comprehensive description of the glacial history of the Sierra Nevada he recognized four glacial stages.  This was not because of widespread evidence for four advances, rather, it was because four stages were required by the prevailing paleoclimatic theory of his day.  In fact, while there is abundant evidence of the two most recent advances, that for Blackwelder’s two older stages is exceedingly fragmentary.  Blackwelder named the penultimate and the most recent glacial stages the ‘Tahoe’ and the ‘Tioga’, respectively.  Today, chronology provided mainly by cosmogenic nuclide accumulation dating, but supplemented by other methods, has demonstrated that the Tahoe is contemporaneous with the global glacial maximum of Marine Isotope Stage (MIS) 6 (~140 ka) and the Tioga with the maximum of MIS 2 (~20 ka).  Given that the severity of preceding glacial stages in the marine isotope record is very similar to these two stages, it seems highly likely that the Sierra Nevada over the past million years has undergone multiple glaciations of similar magnitude to the Tahoe and Tioga.  This is at least partially confirmed by geochemical evidence from a core in Owens Lake sediments that extends back to ~800 ka.  It shows multiple cycles of wet conditions very similar to the Tahoe and Tioga and dry conditions similar to the Holocene.  These cycles follow the same chronology as the Marine Isotope Stages.

The history of the deglaciation of the Sierra Nevada at the end of MIS 2 can be reconstructed in considerable detail, unlike previous advances and retreats for which the evidence has been destroyed by subsequent glacial erosion.  The evidence indicates that the glaciers reached a position close to that of the terminal moraine by 26 ka, well before the global Last Glacial Maximum at about 20 ka.  The terminal position was occupied from about 21 to 19 ka.  Between 19 and 16.7 ka the glaciers retreated far back in the range.  Between 16.7 and 16.2 ka they readvanced, eventually reaching about one-third of the glacial maximum extent.  At 16.2 ka they retreated very rapidly, deglaciating the Sierra Nevada, except perhaps for a few very small cirque glaciers.  There is no indication of subsequent glacial expansion until the diminutive Recess Peak advance between 14.0 and 12.5 ka. Whether this coincided with the quasi-global Younger Dryas event (12.9-11.6 ka) is uncertain.

During the early Holocene, even the tiny cirque glaciers apparently disappeared.  These re-formed at about 3 ka and advanced until the termination of the Little Ice Age at the end of the Nineteenth Century.  Today they are rapidly disappearing as Global Warming renders the Sierra Nevada unsuitable for glaciers.

In the end, the 74 people in attendance heard a presentation on the tephrochronology of the Monterey and Modelo Formations. Many of the samples were collected during grading operations here in Orange County. Hopefully, not too many people were disappointed and we will try and get Sue Hough at a future meeting to tell us about the Northridge earthquake.

McMichael, Ryan (CSUF – Undergraduate)

“Unveiling the Secrets of Marine Terrace Rings: A Window into Paleoenvironmental Change and Ecological Shifts”

Munoz, Jonathan (CSUF – Undergraduate)

“Uncovering Hidden Influence: Unconventional Non-Demographic Variables Shape Success and Close Educational Gaps in Introductory Geology”

Onderdonk, Nate (CSULB – Professor)

“Paleomagnetic directions and Argon dating of Miocene rocks show unusually rapid vertical-axis rotation on Santa Catalina Island, offshore southern California“

Ortega, Sonny (CSUF – Undergraduate)

“Assessing the role of wood fragments in the formation of calcite concretions of the Late Cretaceous Holz Shale, Santa Ana Mountains“

Ruiz, Roberto (CSUF – Undergraduate)

“Rancho Mission Viejo Riding Park Recharge System“

Scandore, Alex (CSULB – Undergraduate)

“Alteration and hydrothermal fluid provenance in the Lima Segment of the Peruvian Coastal Batholith”

Walters, Polito (CSULB)

“Hydrothermal Alteration Related to the Brittle-Ductile Transition at the Sierra Crest Shear Zone, Eastern Sierra Nevada, California”

Wilkins, Shaun (Langan – Professional)

“500-foot Slip or Slide”

Woodard, Brennen (CSUF – Undergraduate)

“The Requirements for Constructing a Favorable Recharge Well in San Juan Capistrano, California”

Abstract:

Cone Penetrometer Test (CPT) soundings are an often-used method to characterize subsurface soil behavior properties mostly in soft material conditions. The method has many geotechnical applications, some of which include liquefaction analysis, mapping of alluvial deposits and fill, evaluation of soil density improvement and determination of seismic S- and P-wave velocities. When a series of CPTs is advanced, the subsurface stratigraphy can be profiled. This was recognized early on and soon CPTs were engaged to identify stratigraphic disruptions indicative of faulting. This method is now widely used in the coastal province of Southern California, mostly in upper Quaternary materials. Oftentimes, only several feet or less of vertical differential across unit horizons or thickness variations in strata are used to identify potential faulting. This means it is imperative that depth recording of CPTs are as accurate as possible.

Several factors can cause errors in depth readings, leading to erroneous interpretations of faulting. These factors will be discussed in this presentation as well as a quality control procedure to track actual depths and thus mitigate errors. In addition, several examples will be presented where inaccurate depth readings resulted in misinterpretation of faulting. Finally, both the advantages and limitations of the CPT method will be discussed.

Abstract:

New Mexico offers spectacular geology sites such as mesas, volcanic necks, arches, and gorges, but Paul, after presenting four regional geology features of the state, will focus on geologic sites unique to New Mexico including two subsurface atomic explosion experiments, a large magma body, an actively produced CO2 field, and special geology of the Permian Basin and its evaporites.

Abstract: 

Lithium: the hot metal everyone can’t get enough of. With the push for increased electrification, the world needs more electrical storage (batteries) requiring more and more lithium. Found all over the earth, lithium is ultimately derived from two geological sources: brines and hard rock pegmatites. Rarely forming in minerals, this metal is often concentrated only in the final stages of magmas. As our need for lithium grows, we will need to exploit new sources: some well known but uneconomical and some yet to be discovered. This talk will serve as an overview of the geology of lithium deposits while explaining why we find lithium where we do. We will also explore the global lithium market, the future the US and California may play in it, and how upcoming technologies may completely change how we approach lithium resources.

Abstract:

This talk provided a whirlwind tour of the Alpine Fault in New Zealand, often considered one of the world’s “big three” active continental strike-slip fault systems (alongside Turkey’s North Anatolian and the San Andreas). The fast slip rate (∼30 mm/yr), regular recurrence interval (249 ± 58 yr), and time of last earthquake (1717 CE) yield a 75% probability of Alpine Fault surface rupture in the next 50 years, making this one of the world’s most anticipated earthquakes and distinct national-level hazards. The race is on for scientists to learn what they can and communicate it into actionable policy and planning before this earthquake strikes. This talk will provide an overview of our state of knowledge, including the most spatiotemporally complete paleoearthquake record in the world and new lidar-revealed insights into earthquake displacements, slip rates, uplift rates, and landscape effects. A spotlight will be placed on a recent study that used curved scratches (slickenlines) on fault surfaces to constrain the rupture locations of past Alpine Fault earthquakes, demonstrating the utility of a brand new paleoseismological tool applicable to surface-rupturing faults globally.