James W. (James William) Head.

History and comprehensive description of Loudoun County, Virginia [electronic resource] online

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Online LibraryJames W. (James William) HeadHistory and comprehensive description of Loudoun County, Virginia [electronic resource] → online text (page 2 of 15)
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Hills, another range commencing at the Potomac River about
four miles below Harpers Ferry and extending parallel to the
Blue Ridge, at a distance of nearly four miles from summit to
summit, for about twelve miles into the County, where it is
broken by a branch of Catoctin Creek. Beyond this stream
it immediately rises again and extends about three miles
further, at which point it abruptly terminates.

A third range, called "Catoctin Mountain," nas its incep-
tion in Pennsylvania, traverses Maryland, is interrupted by
the Potomac, reappears in Virginia at the river margin, oppo-
site Point of Rocks, and extends through Loudoun County
for a distance of twenty or more miles, when it is again

Elevations on Catoctin Mountain progressively diminish
southward from the Potomac River to Aldie, although the rocks
remain the same, and the Tertiary drainage, which might be
supposed to determine their elevations, becomes less effective
in that direction.

Probably this mountain does not exceed an average of more
than 300 feet above the surrounding country, though at
some stages it may attain an altitude of 700 feet. Rising
near the Potomac into one of its highest peaks, in the same
range it becomes alternately depressed and elevated, until


reaching the point of its divergence in the neighborhood of
Waterford. There it assumes the appearance of an elevated
and hilly region, deeply indented by the myriad streams that
rise in its bosom.

On reaching the I^eesburg and Snicker's Gap Turnpike
road, a distance of twelve miles, it expands to three miles in
width and continues much the same until broken by Goose
Creek and its tributary, the North Fork, when it gradually
loses itself in the hills of Goose Creek and Little River, before
reaching the Ashby's Gap Turnpike.

The Catoctin range throughout Loudoun pursues a course
parallel to the Blue Ridge, the two forming an intermediate
valley or base-level plain, ranging in width from 8 to 12 miles,
and in altitude from 350 to 730 feet above sea level. Allusion
to the physiography of this valley — so called only by reason
of its relation to the mountains on either side — has been made
elsewhere in this department.

Immediately south of Aldie, on Little River, near the point
of interruption of Catoctin Mountain, another range com-
mences and extends into Fauquier County. It is known as
"Bull Run Mountain," but might rightly be considered an
indirect continuation of the elevation of the Catoctin, its
course and some of its features corresponding very nearly
with that mountain save only that it is higher than any of the
ranges of the latter, excepting the western.

East of the Catoctin the tumultuous continuity of moun-
tains subsides into gentle undulations, an almost unbroken
succession of sloping elevations and depressions presenting an
as yet unimpaired variety and charm of landscape. However,
on the extreme eastern edge of this section, level stretches of
considerable extent are a conspicuous feature of the topog-

Three or four detached hills, rising to an elevation of 1
or 200 feet above the adjacent country, are the only ones of
consequence met with in this section.



The hilly character of Loudoun is clearly shown by the
following exhibit of the elevation of points and places above
tidewater. The variations of altitude noted in this schedule
are based upon conflicting estimates and distinct measure-
ments made at two or more points within a given circumfer-
ence and slightly removed one from the other.


Sterling 4l5

Ashburn 320

Leesburg 321 to 337

Clarke's Gap 578 to 634

Hamilton 454 to 521

Purcellville 546 to 553

Round Hill 558

Bluemont 680 to 730

Snicker's Gap 1 ,085

Neersville 626

Hillsborough 550

Waterf ord 36O

Mount Gilead 600

Oatlands 270

Little River, near Aldie 299

Middleburg 48O

Potomac River, near Seneca Dam 188

Potomac River, at Point of Rocks 200

Potomac River, at Harper's Ferry 246

The whole of the county east of the Catoctin Mountain
varies from 200 to 350 feet. The eastern base of the Blue
Ridge has an elevation of about 730 feet, and the highest
peak of that range in Loudoun rises 1 ,600 feet above tide- water.
The Short Hills have an approximate altitude of 1,000 feet,
while that of the Catoctin Mountain varies from 3OO to 700
feet. The valley between the Blue Ridge and Catoctin Moun-
tains varies from 350 to 730 feet in elevation.


From many vantage points along the Blue Ridge may be
obtained magnificent views of both the Loudoun and Shenan-
doah valleys. The eye travels entirely across the fertile
expanse of the latter to where, in the far distance, the Alle-
ghany and North Mountains rear their wooded crests. A few
of the summits offer even more extensive prospects. From
some nearly all of Loudoun, with a considerable area of Fair-
fax and Fauquier, is in full view. Other more distant areas
within visionary range are portions of Prince William, Rap-
pahannock, and Culpeper counties, in Virginia, Frederick and
Montgomery counties, in Maryland, and even some of Prince
George County, east of Washington City. Westward, the
view embraces Shenandoah, Frederick, Clarke and Warren
counties, in Virginia, Berkeley and Jefferson counties, in West
Virginia, Washington County, in Maryland, and some of the
mountain summits of Pennsylvania.


The drainage of Loudoun can be divided into two provinces.
One is the Potomac province, which is drained by a system of
small tributaries of that stream. Its elevations are quite uni-
form and are referable to that master stream, whose grade is
largely determined by its great basin beyond the **Catoctin
belt. ' ' The second province is the region drained by smaller
streams, chief of which is Goose Creek. In this province the
drainage lines head entirely within the "Catoctin belt, ' ' and the
elevations are variable according to the constitution of the
rocks in the belt itself.

The tributaries by which the drainage of the two provinces
is effected are Catoctin Creek, North Fork Catoctin Creek,
South Fork Catoctin Creek, Little River, North Fork Goose
Creek, Beaver-dam Creek, Piney Run, Jeffries Branch, Crom-
wells Run, Hungry Run, Bull Run, Sycoline Creek, Tuscarora
Creek, Horse Pen Run, Broad Run, Sugarland Run, Elk Lick,
Limestone Branch, and as many lesser streams.


The general slope of the county being to the northeast, the
waters, for the most part, naturally follow the same course,
as may be readily perceived by reference to maps of the sec-
tion. The streams that rise in the Blue Ridge mostly flow to
the eastward until they approach the Catoctin Mountain,
where they are then deflected more toward either the north
or south to pass that range by the Northwest Fork and Goose
Creek, or by the Catoctin Creek which falls into the Potomac
above Point of Rocks. East of Catoctin Mountain the
streams pursue a more or less direct northern course.

Goose Creek, a right-hand branch of the Potomac River,
is a considerable stream, pursuing a course of about fifty
miles from its source in Fauquier County to its junction with
the Potomac four miles northeast of I^eesburg. It once bore
the Indian name Gohongarestaw , meaning '' River of Swans."
Flowing northeastward across lyoudoun, it receives many
smaller streams until passing the first range of Catoctin
Mountain, when it claims a larger tributary, the North Fork.
Goose Creek represents subsequent drainage dependent on
the syncline of the Blue Ridge and dating back at least as far as
Cretaceous time. Its length in I^oudoun is about thirty miles,
and it has a fall of one hundred feet in the last twenty-two
miles of its course. It drains nearly one-half the county and
is about sixty yards wide at its mouth.

Catoctin Creek is very crooked ; its basin does not exceed
twelve miles as the crow flies, and includes the whole width
of the valley between the mountains except a small portion
in the northeastern angle of the County. Yet its entire course,
measuring its meanders, would exceed thirty-five miles. It
has a fall of one hundred and eighty feet in the last eighteen
miles of its course, and is about twenty yards wide near its

The Northwest Fork rises in the Blue Ridge and flows
southeastward, mingling its waters with the Beaver Dam,
coming from the southwest, immediately above Catoctin
Mountain, where their united waters pass through a narrow
valley to Goose Creek.


Little River, a small affluent of Goose Creek, rises in Fau-
quier County west of Bull Run mountain and enters Loudon
a few miles southwestward of Aldie. It pursues a northern
and northeastern course until it has passed that town, turning
then more to the northward and falling into Goose Creek.
Before the Civil War it was rendered navigable from its
mouth to Aldie by means of dams.

Broad Run, the next stream of consequence east of Goose
Creek, rises in Prince William County and pursues a northern
course, with some meanderings through Loudoun. It flows
into the Potomac about four miles below the mouth df Goose

Sugarland Run, a still smaller stream, rises partly in
Loudoun, though its course is chiefly through Fairfax County,
and empties into the Potomac at the northeastern angle of the

In its southeastern angle several streams rise and pursue a
southern and southeastern course, and constitute some of the
upper branches of Occoquan River.

Perhaps no county in the State is better watered for all
purposes, except manufacturing in times of drought. Many
of the farms might be divided into fields of ten acres each
and, in ordinary seasons, would have water in each of them.

There are several mineral springs in the county of the class
called chalybeate, some of which contain valuable medicinal
properties, and other springs and wells that are affected with
lime. Indeed, in almost every part of the County, there is an
exhaustless supply of the purest spring water. This is due,
in great part, to the porosity of the soil which allows the
water to pass freely into the earth, and the slaty character of
the rocks which favors its descent into the bowels of the hills,
from whence it finds its way to the surface, at their base, in
numberless small springs. The purity of these waters is bor-
rowed from the silicious quality of the soil.

The largest spring of any class in the county is Big Spring, a
comparatively broad expanse of water of unsurpassed quality,
bordering the Leesburg and Point of Rocks turnpike, about
two miles north of Leesburg.


The springs, as has been stated, are generally small and
very numerous, and many of them are unfailing, though lia-
ble to be affected by drought. In such cases, by absorption
and evaporation, the small streams are frequently exhausted
before uniting and often render the larger ones too light for
manufacturing purposes. Nevertheless, water power is abun-
dant; the county's diversified elevation giving considerable
fall to its water courses, and many sites are occupied.


Because responsible statistical data is usually accorded un-
qualified credence, it is without undue hesitation that the
following bit of astonishing information, gleaned from a
reliable source, is here set down as positive proof of the ex-
cellence of lyoudoun's climate: "It (Leesburg) is located in
a section the healthiest in the world, as proven by statistics
which place the death rate at S]4 per 1,000, the very lowest
in the table of mortality gathered from all parts of the hab-
itable globe."

The climate of Loudoun, like that of most other localities,
is governed mainly by the direction of the prevailing winds,
and, to a limited extent, is influenced by the county's diversi-
fied physical features.

Though the rainfall is abundant, amounting annually to
forty or fifty inches, ordinarily the air is dry and salubrious.
This ample precipitation is usually well distributed through-
out the growing season and is rarely insufl&cient or excessive.
The summer rainfall comes largely in the form of local
showers, scarcely ever attended by hail. Loudoun streams
for the most part are pure and rapid, and« there appears to be
no local cause to generate malaria.

In common with the rest of Virginia the climate of Loudoun
corresponds very nearly with that of Cashmere and the best
parts of China. The mean annual temperature is 50° to 55°.

Loudoun winters are not of long duration and are seldom



marked by protracted severity. Snow does not cover the
ground for any considerable period and the number of bright
sunny days during these seasons is unusually large. In their
extremes of cold they are less rigorous than the average
winters of sections farther north or even of western localities
of the same latitude. Consequently the growing season here
is much more extended than in either of those sections. The
prevailing winds in winter are from the north and west, and
from these the mountains afford partial protection.

The seasons are somewhat earlier even than in the Shenan-
doah Valley, just over the western border of lyoudoun, and
the farmers here plant and harvest their crops from one week
to ten days earlier than the farmers of that region.

Loudoun summers, as a rule, are long and agreeably cool,
while occasional periods of extreme heat are not more oppres-
sive than in many portions of the North. The mountains of
lyoudoun have a delightful summer climate coupled with
inspiring scenery, and are well known as the resort of
hundreds seeking rest, recreation, or the restoration of health.
This region, owing to its low humidity, has little dew at
night, and accordingly has been found especially beneficial
for consumptives and those afflicted with pulmonary diseases.
The genial southwest trade winds, blowing through the long
parallel valleys, impart to them and the enclosing mountains
moisture borne from the far away Gulf of Mexico.


The geology of more than half the area of Loudoun County
has received thorough and intelligent treatment at the hands
of Arthur Keith in his most excellent work entitled * * Geology
of the Catodin Belt,'" authorized and published by the United
States Geological Survey.*

*♦ Credit for many important disclosures and much of the detail ap-
pearing in this department is unreservedly accorded Mr. Keith and his


Mr. Keith's analysis covered the whole of Bull Run Moun-
tain, the Catoctin in its course through Virginia and Mary-
land to its termination in southern Pennsylvania, the Blue
Ridge and South Mountain for a corresponding distance, all
intermediate ridges and valleys and contiguous territory
lying outside this zone and paralleling the two flanking

In this important work the Catoctin Belt is shown to be an
epitome of the leading events of geologic history in the Ap-
palachian region. It contains the earliest formations whose
original character can be certified; it contains almost the
latest known formations; and the record is unusually full,
with the exception of the later Paleozoic rocks. Its structures
embrace nearly every known type of deformation. It furnishes
examples of every process of erosion, of topograph}^ derived
from rocks of nearly every variety of composition, and of
topography derived from all types of structure except the flat
plateau type. In the recurrence of its main geographic
features from pre-Cambrian time till the present day it fur-
nishes a remarkable and unique example of the permanence
of continental form.

With certain qualifications, a summary of the leading events
that have left their impress on the region is as follows:

1. Surface eruption of diabase.

2. Injection of granite.

3. Erosion.

4. Surface eruption of quartz-porphyry, rhyolite, and

5. Surface eruption of diabase.

6. Erosion.

7. Submergence, deposition of Cambrian formations; slight
oscillations during their deposition; reduction of land to base-

*The name*' Catoctin Belt "is applied to this region because it is
separated by Catoctin Mountain from the Piedmont plain as a geo-
graphic unit more distinctly than in any other area, and because its
geological unity is completed by Catoctin more fully and compactly
than elsewhere.


8. Eastward tilting and deposition of Martinsburg shale;
oscillations during later Paleozoic time.

9. Uplift, post- Carboniferous deformation and erosion.

10. Depression and Newark deposition; diabase intrusion.

11. Uplift, Newark deformation; and erosion to Catoctin

12. Depression and deposition of Potomac, Magothy, and

13. Uplift south westward and erosion to baselevel.

14. Uplift, warping and degradation to Tertiary baselevel;
deposition of Pamunkey and Chesapeake.

15. Depression and deposition of I^afayette.

16. Uplift and erosion to lower Tertiary baselevel.

17. Uplift, warping and erosion to Pleistocene baselevel;
deposition of high-level Columbia.

18. Uplift and erosion to lower Pleistocene baselevel; dep-
osition of low-level Columbia.

19. Uplift and present erosion.

Along the Coastal plain reduction to baselevel was followed
by depression and deposition of lyafayette gravels; elevation
followed and erosion of minor baselevels; second depression
followed and deposition of Columbia gravels; again comes
elevation and excavation of narrow valleys; then depression
and deposition of low-level Columbia; last, elevation and
channeling, which is proceeding at present. Along the
Catoctin Belt denudation to baselevel was followed by depres-
sion and deposition of gravels; elevation followed and erosion
of minor baselevels among the softer rocks; second depression
followed, with possible gravel deposits; elevation came next
with excavation of broad bottoms; last, elevation and chan-
neling, at present in progress.

The general structure of the Catoctin Belt is anticlinal.
On its core appear the oldest rocks; on its borders, those of
medium age; and in adjacent provinces the younger rocks.
In the location of its system of faulting, also, it faithfully
follows the Appalachian law that faults lie upon the steep side
of anticlines.


After the initial location of the folds along these lines, com-
pression and deformation continued. Yielding took place in
the different rocks according to their constitution.

Into this system of folds the drainage lines carved their
way. On the anticlines were developed the chief streams, and
the synclines were left till the last. The initial tendency to
synclinal ridges was obviated in places by the weakness of
the rocks situated in the synclines, but even then the tendency
to retain elevation is apt to cause low ridges. The drainage
of the belt as a whole is anticlinal to a marked degree, for
the three main synclinal lines are lines of great elevation, and
the anticlines are invariably valleys.

In order of solubility the rocks of the Catoctin Belt, within
the limits of lyoudon County, to which section all subsequent
geologic data will be confined, stand as follows:

1. Newark limestone conglomerate; calcareous.

2. Newark sandstone and shale; calcareous and felds-

3. Newark diabase; feldspathic.

4. Granite; feldspathic.

5. Loudoun formation; feldspathic.

6. Granite and schist; feldspathic.

7. Catoctin schist; epidotic and feldspathic.

8. Weverton sandstone; siliceous.

All of these formations are in places reduced to baselevel.
The first three invariably are, unless protected by a harder
rock; the next three usually are; the Catoctin schist only in
small parts of its area; the Weverton only along a small part
of Catoctin Mountain.

The Catoctin Belt itself may be described as a broad area of
igneous rocks bordered by two lines of Lower Cambrian
sandstones and slates. Over the surface of the igneous rocks
are scattered occasional outliers of the Lower Cambrian slate;
but far the greater part of the surface of the belt is covered
by the igneous rocks. The belt as a whole may be regarded
as an anticline, the igneous rocks constituting the core, the


Lower Cambrian the flanks, and the Silurian and Newark the
adjoining zones. The outcrops of the Lower Cambrian rocks
are in synclines, as a rule, and are complicated by many
faults. The igneous rocks have also been much folded and
crumpled, but on account of their lack of distinctive beds the
details of folds can not well be traced among them.

They are the oldest rocks in the Catoctin Belt and occupy
most of its area. They are also prominent from their unusual
character and rarity.

An important class of rocks occurring in the Catoctin Belt
is the sedimentary series. It is all included in the Cambrian
period and consists of limestone, shale, sandstone and con-
glomerate. The two border zones of the Catoctin Belt, how-
ever, contain also rocks of the Silurian and Juratrias periods.
In general, the sediments are sandy and calcareous in the
Juratrias area, and sandy in the Catoctin Belt. They have
been the theme of considerable literature, owing to their great
extent and prominence in the topography.


The granite in the southern portion of the County is very
important in point of extent, almost as much so as the diabase
in the same section.

The areas of granite are, as a rule, long narrow belts, and
vary greatly in width.

The mineralogical composition of the granite is quite con-
stant over large areas. Six varieties can be distinguished,
however, each with a considerable areal extent. The essential
constituents are quartz, orthoclase and plagioclase, and by
the addition to these of biotite, garnet, epidote, blue quartz,
and hornblende, five types are formed. All these types are
holocrystalline, and range in texture from coarse granite
with augen an inch long down to a fine epidote granite with
scarcely visible crystals.

Loudoun Formation.

Among the various Cambrian formations of the Catoctin
Belt there are wide differences in uniformity and composition.


In none is it more manifest than in the first or Loudoun
formation. This was theoretically to be expected, for first
deposits upon a crystalline foundation represent great changes
and transition periods of adjustment among new currents and
sources of supply. The Loudoun formation, indeed, runs the
whole gamut of sedimentary possibilities, and that within
very short geographical limits. Five miles northwest of
Aldie the Loudoun formation comprises limestone, slate, sandy
slate, sandstone, and conglomerate with pebbles as large as
hickory nuts. These amount in thickness to fully 800 feet,
while less than three miles to the east the entire formation is
represented by eight or ten feet of black slate.

The name of the Loudoun formation is given on account of
the frequent occurrence of all its variations in Loudoun
County. Throughout the entire extent of the Catoctin Belt,
and especially through its central portions, the Loudoun
formation has frequent beds of sandstone, conglomerate, and
limestone. The limestones occur as lenses along two lines;
one immediately west of Catoctin Mountain, the other three
or four miles east of the Blue Ridge. Along the western
range the limestone lenses extend only to the Potomac. There
they are shown on both sides of the river, and have been
worked in either place for agricultural lime. Only the refuse
of the limestone now remains, but the outcrops have been
extant until recent years. Along the eastern line the lime-
stone lenses extend across the Potomac and into Maryland
for about one mile, and it is along this belt that they are
the most persistent and valuable. As a rule they are altered
from limestone into marble, and at one point they have been
worked for commercial purposes. Nearly every outcrop has
been opened, however, for agricultural lime. Where Goose
Creek crosses this belt a quarry has been opened and good
marble taken out, but want of transportation facilities has
prevented any considerable development. The relation be-
tween marble and schist is very perfectly shown at an old
quarry west of Leesburg. The marble occupies two beds in
schist, and between the two rocks there is gradation of com-
position. In none of the western belts are the calcareous


beds recrystallized into marbles, but all retain their original
character of blue and dove-colored limestone. None of them,
however, is of great thickness and none of great linear extent.

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Online LibraryJames W. (James William) HeadHistory and comprehensive description of Loudoun County, Virginia [electronic resource] → online text (page 2 of 15)