2000 December

Geological Report for Erla GPS CORS

Following is a slightly amended excerpt from the  Erla Log file available at


1. Site Identification of the GPS Monument

Site Name : Erlanger
Four Character ID : ERLA
Monument Inscription :
IERS DOMES Number : 49859S001
CDP Number : (XXXX)
Date Installed : 14-SEP-1996 UT
Geologic Characteristic : BEDROCK
Bedrock Type : SEDIMENTARY
Bedrock Condition : WEATHERED
Fracture Spacing : Generally not fractured
Notes : Ordovician-aged shale and thinly bedded
: limestone (430,000,000+ years old)
Additional Information : Bedrock is horizontally bedding, relatively unfractured and unjointed and stable.

[Geological characterization and details provided by a locally-based professional geologist, Covington, KY. 07-Dec-2000]:
The ERLA site located at 463 Erlanger Road, Erlanger, KY is situated near the epicenter of a geologically stable regional area known as the "Cincinnati Arch", which is a very broad positive platform founded in south central Kentucky and extending 30-50 miles into SE Indiana and SW Ohio.  Local to Erla, the formation is a northeast trending, slightly plunging anticline. The Erlanger area is located at the top of the "arch" where the bedding is nearly horizontal.  Long term erosion has exposed the Ordovician-aged shale and thinly bedded limestone bedrock.  The bedrock is generally overlain by shallow glacial and residual soil deposits that are stiff to very stiff in consistency and approximately 5 to 10 feet thick over the bedrock. The underlying bedrock formations from the surface to approximately 500 feet below the site are known as:

  1. Bull Fork Formation,
  2. Bellevue Tongue of the Grant Lake Limestone,
  3. Fairview Formation,
  4. Kope Formation;

all which are composed of interbedded shale and crystalline to fossiliferous limestone of varying percentages.
The bedrock is generally characterized according to the degree of weathering. The uppermost zone directly below the soil is known as the brown highly weathered shale and thinly bedded limestone where the shale component has nearly weathered into a soil, yet still retains distinct bedding planes. This highly weathered zone overlies the less weathered olive brown weathered shale and thinly bedded limestone.  Both the highly weathered and weathered zones originated from the parent bedrock, the unweathered gray shale and thinly bedded limestone bedrock. The tri-state region (Northern KY, SouthEastern IN, and SouthWestern OH) is also known for relatively low seismicity as recorded within historic time.

DOMES number added

__________end of CORS log file. _______________________________

Antenna Mount

The Erla Antenna is mounted on a masonry column founded on stone foundation on the crest of the Cincinnati Arch.  The concrete base of the chimney, 42"x 90" is integrated with the building foundation by a horizontal tie to the inner, NE perimeter foundation for the main building core.  Additional concentric extensions of the foundation occur on both ends of the building in the NE - SW direction aligned with the long axis of the chimney.  The 30" x 60", 4-flue, brick chimney is central to the main body of the building:  a 3-story, 36' x 17' rectangle under original A-frame slate roof.  The Southern-most flue is plugged with a 10' column of concrete reinforced with 2 1/2" rebar, which extends 10' above the top of the chimney in a 6" galvanized steel pipe also filled with concrete, founded at 2' below the roof-line.  The pipe is capped with an adapter for the antenna mount.

Below the roof line, the chimney is supported by the building framing including wall partitions, and floor frames at the following approximate elevations from its base 5' below grade:  7', 17', 27' and roof at 35'.  The frame construction, since 1895, has rigidified under constant weight of the slate roof, converging the stability of the 3D, founded frame to the central chimney column.