geologic cross section se beverley hills...290 189 178 gt-42 55 25 39 gt-191 155 121 gtb-88 155 140...
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GT-42 55
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GT-191 155
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GTB-88 155140
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GT-147 96
GT-41 41
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GT-181 38
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GT-165 45
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Totaldepth
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F-5 38
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%
tota
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se o
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GT133-18 42
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GT-5/16 49
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GT133-1 43
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F-6 48
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GT-143 45
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GT-146 47
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GT-139 47
28
-400
D-14 30
Did
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ck
GT-35 26
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5
Mount Ida
Mt Vernon Ave
Del RayFourMileRun
Beverley Park
Old Dominion Blvd
Monticello Park
Russell Road
Jefferson Park
Beverley Hills
Old TownNorth End
FOUR MILE RUN
MOUNT IDA
POTOMAC YARDS
EISENHOWER VALLEY
OLD TOWN
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NW C SEC’
BEVERLEY HILLS GEOLOGIC CROSS SECTION
by Anthony H. Fleming, 2015
City of Alexandria, Virginia Geologic Atlas of the City of Alexandria, Virginia and Vicinity – Plate 2C
1000 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
FEET
VERTICAL EXAGGERATION 20XSEE PLATE 5 FOR EXPLANATION OF MAP UNITS
EXPLANATION OF CROSS SECTION SYMBOLS:
WATER WELLWELL ID NUMBER AND SURFACE ELEVATION(SOURCE: J-JOHNSTON; D-DARTON; F-FROELICH)
WELL CASING
WATER LEVEL
WELL SCREEN
REPORTED BEDROCK LITHOLOGY
BOTTOM ELEVATION
% SAND IN 100-FT INTERVAL REPORTED BY FROELICH (1985)
BEDROCK SURFACE
BOREHOLE IN BEDROCK
sch
ist
147
J-60 250
195
70
% s
an
d1
0%
sa
nd
GEOTECHNICAL BORING SITES
127
GT-27 222
147
ID NUMBER AND HIGHEST SURFACE ELEVATION
APPROXIMATE LATERAL ANDVERTICAL EXTENT OF SITEALONG CROSS SECTION LINE
WATER LEVEL
BOTTOM ELEVATION OF DEEPEST BORING
GT133-15 42
2
17
NOTE: GEOTECHNICAL BORING SITE #133 CONSISTS OF 25 BORINGS DISTRIBUTED ALONG THE ROUTE OF A TWO MILE LONG TRUNK SEWER. ICONS SHOWN ON THE CROSS SECTION INDICATE THE LOCATIONS, IDENTITIES, DEPTHS, AND WATER LEVELS OF THE INDIVIDUAL BORINGS
119
210
132
WATER LEVELS REPORTED IN WELLS AND GEOTECHNICAL BORINGS
WATER LEVEL MEASURED IN WELL ORCASED GEOTECHNICAL BORING COMPLETEDIN THE CAMERON VALLEY SAND (LOWERAQUIFER OF THE POTOMAC FORMATION)
WATER LEVEL MEASURED IN 1976 FROM WELL COMPLETED IN CAMERON VALLEY SAND (JOHNSTON AND LARSON, 1977)
WATER LEVEL MEASURED IN WELL OR GEOTECHNICAL BORING COMPLETED INOTHER AQUIFERS. MAY REPRESENT A COMPOSITE OR AVERAGE WATER LEVEL AT GEOTECHNICAL SITES WITH MANY BORINGS
OTHER SYMBOLS
SURFACE EXPOSURE. SOME EXCAVATIONS COINCIDE WITH GEOTECHNICAL BORING SITES
GRAVELLY ZONES IN THE OLD TOWN TERRACE REPORTED IN GEOTECHNICAL BORINGS
ORGANIC ZONES REPORTED IN GEOTECHNICALBORINGS FROM THE POTOMAC FORMATION, QUATERNARY ALLUVIUM, AND OTHER SEDIMENTS.INCLUDES WOOD, PEAT, LIGNITE, LEAVES, DARKORGANIC SILT, AND OTHER ORGANIC MATERIAL
INTERSECTION WITH ANOTHER CROSS SECTION.CROSS SECTIONS ARE DISTINGUISHED BY NAMEAND COLOR-CODED SECTION LINES AND TITLES
SPECULATIVE POST-CRETACEOUS FAULT OR FLEXURE ASSOCIATED WITH THE ROCK CREEKSHEAR ZONE
47
g
ORG
MOUNT IDA
The cross sections are intended to be used together with the The large gravel-filled channel beneath Old Town is recognized in GEOLOGIC CROSS SECTION 2C– BEVERLEY HILLSother maps, particularly Plate 5, to illustrate the third dimension of a few geotechnical boring sites and appears in other cross Cross section 2C extends southeast from near the map units. Contacts between map units are approximately sections that traverse Old Town. the Old Town waterfront. The section traverses nearly the entire located; the abundance of control points (surface exposures, width of the Old Town terrace between Old Town and Del Ray, as wells, geotechnical boring sites) along the cross section provides By virtue of its orientation, the Beverley Hills cross section well as a large swath of the northeastern highlands. The view is a general indication of the reliability of contact locations. Map probably comes the closest of all the sections to paralleling the generally to the northeast along the section line, which locally units are depicted using the same colors, patterns, and labels as regional dip of the bedrock surface and the depositional axis of bends to take in the locations of nearby geotechnical boring sites, on Plate 5, and the explanation of map units on Plate 5 serves as the Potomac Formation. Heterogeneous sediments of the historical water wells, and significant natural areas (e.g., the legend. The section also depicts some bedrock units and a Chinquapin Hollow member make up the great bulk of the outcrop Monticello and Beverley Parks) where many outcrops are few gravelly zones in the Old Town terrace that are present only area of the formation in this section; however, the character of the present. These features, and other sites of cultural, historical, and in the subsurface, and thus do not appear on Plate 5. formation at depth, and the eastward continuity of the individual environmental interest. are indicated by labels and symbols along
The Beverley Hills section illustrates the general eastward units from their outcrop areas further to the west, are highly the cross section. The specific location of the cross section is thickening of the Old Town terrace, as well as local stratigraphic speculative, especially beneath Old Town, where only a handful indicated on Plate 1 by a dark green section line. details, as deduced from subsurface data and geomorphology. of old wells penetrate to such great depth.
City–which separates the relatively level and low-lying Old Town terrace from the elevated and strongly dissected uplands that Four Mile Run to comprise the northeastern quadrant of the City. Part of this scarp coincides with the magnetically defined trace of the Rock Creek Shear Zone, raising the question of whether its location may be partly tectonically influenced. The northward extension of a fault or flexure postulated on sections further south appears as the queried fault at the base of the scarp. The sharp increase in slope of the bedrock surface below Old Town could also be attributable to another fault, as discussed in chapter 8.
The dominant physiographic feature is the east-facing Mount Ida escarpment – one of the most imposing natural landmarks in the
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