Pt.1) Introduction and Geological Background: Building Stone of the Lincoln Memorial, by Elaine S. McGee

An investigation of differences in the durability of the Colorado Yule marble, a widely used building stone.

By Elaine S. McGee.

U.S. GEOLOGICAL SURVEY BULLETIN 2162

Building Stone of the Lincoln Memorial

Abridged and Presented for your Interest and Enjoyment by Martin Cooney

PART 1) INTRODUCTION and GEOLOGICAL BACKGROUND

U.S. Department of the Interior / U.S. Geological Survey

Colorado Yule Marble — Building Stone of the Lincoln Memorial. Prepared in cooperation with the National Park Service Colorado Yule Marble — Building Stone of the Lincoln Memorial By Elaine S. McGee. U.S. DEPARTMENT OF THE INTERIOR: BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY: CHARLES G. GROAT, Director UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1999. Published in the Eastern Region, Reston, Va. For sale by U.S. Geological Survey Information Services Box 25286, Federal Center Denver, CO 80225 Library of Congress Cataloging in Publication Data. Manuscript approved for publication August 13, 1998.

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Hello and welcome to the first in an eight-part series in which we examine a very revealing U.S. government document first published 20 years ago but as pertinent today as the day it was released.  Section by section we will read just what this auspicious body of experts have to say on the whole subject of Colorado Yule Marble in relation to it being used upon the massive exterior of the Lincoln Memorial.

For the sake of convenience I have abridged what was a long and at times repetitive ‘Survey Bulletin’, but now, at last I have all the evidence I need – if you still need convincing that is – that Yule marble’s place within the global marble market is at the absolute top.  Read on and you will discover exactly why this is now accepted fact for marble lovers the world around.

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PART 1) Building Stone of the Lincoln Memorial

by Elaine S. McGee

INTRODUCTION

The Colorado Yule marble, quarried in Marble, Colo., is a very pure white marble, and it has been widely acclaimed for its quality and purity. This marble has been used for many prominent buildings; one of the most notable is the Lincoln Memorial in Washington, D.C.

One of the purest marbles ever quarried

The Colorado Yule marble is a nearly pure calcite marble with minor inclusions of mica, quartz, and feldspar.  Compositions of the calcite and the inclusion phases in the marble are typical for those phases. The calcite grains that compose the marble are irregularly shaped and range from 100 to 600 micrometers in diameter.  The texture of the marble is even, with a slight preferred directional elongation that is visible when the marble is cut in certain directions.

Praised as one of the purest marbles ever quarried, and cited as a rival to the Italian and Greek marbles of classic fame, the Colorado Yule marble was selected and used for the exterior stone of the Lincoln Memorial in Washington, D.C.

Integral to the effect and feeling

Built between 1914 and 1922, the Lincoln Memorial is one of the most visited and treasured memorials in Washington, D.C., and it serves as a symbolic focus for many historic gatherings.  Some believe that the marble, selected for the monument at the urging of the architect Henry Bacon, is integral to the effect and feeling created by the memorial.

Characteristics of the marble that might influence its durability include composition of the calcite, type and composition of inclusion minerals, grain size, texture, and physical properties.  This study was conducted to characterize the Yule marble and to identify any characteristic(s) that might cause its variable durability.

Controversial selection

When the Colorado Yule marble was chosen for the construction of the Lincoln Memorial, its selection was controversial.  The Lincoln Memorial Commission heard testimony questioning the quality and durability of the Colorado Yule marble.

Questions also were raised about the recently opened quarry’s ability to provide the quantity and size of the blocks of marble required for the construction of the Lincoln Memorial.  Additional physical tests of the marble were made in response to these questions, and additional reviews were made of the quarry and the stone quality before the Colorado Yule marble was finally selected.

ACKNOWLEDGMENTS

Steve Moore (National Park Service) helpfully provided copies of items from the National Archives pertaining to the marble and to the construction of the Lincoln Memorial. The study described in this report was conducted as part of a cooperative project between the U.S. Geological Survey and the Denver Service Center of the National Park Service, funded by agreement MT 2150–5–0001.

GEOLOGIC BACKGROUND

Contact Metamorphism

The Colorado Yule marble is quarried near the town of Marble in Gunnison County, located in central Colorado.  It has been called by the trade names Colorado Yule marble and Yule Colorado marble, but the stone comes from the Leadville Limestone of Mississippian age.

The marble was formed by contact metamorphism that occurred during the Tertiary period, following the intrusion and uplift of the nearby granitic Treasure Mountain dome.  Local contact with the heat and pressure from the intrusion of hot granitic magma recrystallized the Leadville Limestone, which elsewhere in Colorado is a dark-blue stone, into a distinctive white marble.

Leadville Limestone

In the vicinity of the quarry, the Leadville Limestone is separated from the overlying and underlying rocks by unconformities. These unconformities may be the reason why some reports about the Colorado Yule marble erroneously place the age of the marble as Silurian instead of Mississippian.

The indistinct nature of the boundaries of the Leadville Limestone, particularly of the lower contacts near the Treasure Mountain dome, also explains the varied thicknesses (166 ft at the quarry on Yule Creek and 239 ft about 2,000 ft southeast of the quarry) that have been reported for the marble beds of the Leadville Limestone.

Massive white bed

The Yule marble occurs as a massive white bed, 166 to 239 ft thick, with outcrops that usually form prominent cliffs.  Its most distinctive and productive occurrence is along the west side of Yule Creek, about 2.5 miles south of where Yule Creek joins the Crystal River.

The Colorado Yule marble quarry is at an elevation of 9,300 ft above sea level on the west side of Treasure Mountain along Yule Creek.

Marble seam is exposed for more than a mile

About 1,400 ft above the valley formed by Yule Creek, a nearly 200-ft-thick bed of the marble is exposed for more than a mile. The marble bed dips at an angle into Treasure Mountain; however, because the metamorphism that formed the marble obscured most traces of bedding in the marble, it has been difficult to determine the angle of dip of the marble.

Lakes (1910) reported that the marble dipped 51° into the mountain; Merrill (1914) reported a dip of 35°; and Vanderwilt (1937) reported that chert bands, which are believed to be parallel to the original bedding, dip 65° southwest in a prospect tunnel a short distance south of the quarry.

Limited fracturing

The quarry openings are located on the thickest portion of the bed where the exposed marble is overlain by a “heavy covering” of rock that prevented erosion and limited fracturing of the marble. Vanderwilt reported that the entire Mississippian formation (that is, the Leadville Limestone) at the quarry is 239 ft thick.

However, Vanderwilt went on to say that only 100–125 ft of this bed consists of salable white marble:  the lower 100 ft is unmarketable interbedded dolomite marble, and the upper 20–40 ft of the bed is also unmarketable because it contains streaks of gray and red.

Blocks of almost any size or thickness

Early reports (Lakes, 1895) stressed the massive nature of the white statuary (best quality) marble beds, emphasizing that the beds could produce blocks of almost any size or thickness.  Lakes (1910) declared that the size of pure statuary blocks that could be produced from this deposit was limited only by the machinery capable of handling it.

In his report to the Lincoln Memorial Commission, Merrill (1914) observed that there were two principal series of joints in the marble (north 70° west, and 20° south of west) and commented that the sizes of blocks obtainable from the quarry would be limited only by the joints and by the occasional chert layers.

Essentially pure-white marble

Knopf (1949) described two sets of fractures or joints: one set runs N. 65° E. and dips about 80° NW.; a second set of discontinuous, en echelon joints is not easily seen, but the joints strike N. 55° W. and dip about 70° SW. Vanderwilt (1937) also described two sets of fractures, classed as “main headers” and “dry seams,” that are important constraints in the quarrying of the marble, but he further stated that despite these difficulties, the quarry can produce large blocks of essentially pure-white marble.

The largest single piece of marble ever quarried

In 1930, the Colorado Yule marble was selected for the Tomb of the Unknown Soldier (in Arlington National Cemetery).

When the 56-ton block of white statuary marble was removed from the Colorado Yule marble quarry for the Tomb of the Unknown Soldier, it was the largest single piece of marble ever quarried.

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An investigation of differences in the durability of the Colorado Yule marble, a widely used building stone.

By Elaine S. McGee.

U.S. GEOLOGICAL SURVEY BULLETIN 2162

Building Stone of the Lincoln Memorial

Abridged and Presented for your Interest and Entertainment by Martin Cooney

PART 1) INTRODUCTION and GEOLOGICAL BACKGROUND

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Next

Pt.2) QUALITY, GRADE, MINERALOGIC and PHYSICAL CHARACTERISTICS of the MARBLE …. Click Here

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The Story of Colorado Yule Marble

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thanks for visiting martincooney.com

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