Geology Phase Work Summary Outline
Hot Springs Creek Valley, Lassen Volcanic National Park
Charles P. Watson, Advanced Geologic Exploration, Inc.
October 29, 2002
Introduction, Scope and Methods:
• 23 weeks of field work (May 22 – October 26, 2002) at 2-4 days/week
• Aerial coverage: Head of the Valley Falls to Park boundary
• 106 spring temperature sample locations
• 97 consistently measured well temperature sample locations
• 66 rock samples
• 23 soil cores
• 2 clay samples
• 1 sediment sample
Geology:
• Accomplishments and limitations
• Geologic and sample location maps
• Bedrock units (oldest to youngest, distribution)
• Terrace or platform units (oldest to youngest, distribution)
• Structure
- Drakesbad Fault, Sifford Mountain Fault, Terminal Geysers Fault,
Flat Iron Ridge fault system, Hat Creek Faults
- North Spring Complex origin hypothesis
• Glacial and fluvial processes
• Geothermal processes (alteration and mineralization)
• Highlights:
- Intense faulting and fracturing over long and involved history
- Orientations: multiple
- Motions: strike-slip and normal
- Origins: tectonic, volcanic, glacial
- New FIRd age and newly discovered underlying units
- Western extent of FIRd
- New unknown units above Panther Creek intrusive
- Devils Kitchen moraine and associated outwash/till/terraces
- A “recent” glacial advance? Age?
- Raised meadow series south of HSCr west of BSL
- Boiling Springs Lake terraces and displaced alluvial fan
- Ranger Canyon and the Ranger Fault, “The Big Hinge”
- Polished Rock, Kelly Knolls, Secret Meadow, Hank-Hank
Meadows, Sifford Gates, Sifford Meadow, Drake Mountain
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Spring Locations and Temperature Surveys
• Sample location maps
• Springs discussions:
- Five temperature Classes
- Cold (5-8°C)
- Cool (9-14°C)
- Tepid (15-29°C)
- Warm (30-45°C)
- Hot (+45°C)
- North Spring Complex
- South Spring Complex
- Hot Springs Creek Surveys
- July 14 Devils Kitchen Blow-out
- East Valley Springs
- Thermal Springs
- Fall flow increase – measure now!
• Well temperature sampling
- Data processing
- Preliminary results
Soil Cores and Field Observations:
• Soil core location map
• Core description sheet
• Core logs
• Highlights:
- Floodplain scour and fill
- Excellent peat core
- Outwash and till depositions
- Ranger Station trench
- Stream cut observations
Future Work
• Continued geologic mapping (2-year program)
• Expanded soil coring studies for moraines, terraces, kames & lakes
• Continued spring monitoring program w/ water chemistry
- At least one more sample round before winter, springs and wells
• Geothermal monitoring program and hazard evaluation investigations
• Subsurface meadow geophysical explorations
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