US Mint in Denver N39 44.397 W104 59.536
Construction of this historical landmark began in 1897 with Cotopaxi granite, a fine-grained gray granite which also used for part of the City and County Building nearby. At some point the builder switched to a granite from near Loveland, CO. The building also extends three stories beneath the ground. An addition in 1936 used Vermont and Maine Granite. Tennessee marble is in window trim, and Vermont marble is in the interior. The interior of the Mint is currently closed to daily walk-up tours; you need to make an appointment. The exterior fence was added later, made from a nice coarse-grained pink Pikes Peak Granite.
Denver City and County Building - 1437 Bannock Street N39 44.356 W104 59.442
Built in 1932, this Greek Revival building is made of blocks of fine-grained Colorado Cotopaxi gray granite with some marble detailing. This granite ran out, however, so the upper levels and the 50-foot exterior columns are made of Georgia granite with pink Tennessee marble, Fleur de Peche, as decorative insets. Inside, pink Tennessee marble also covers the floors and stairs and contains stylolites. The interior has eleven different marble varieties (pinkish gray from Tennessee, white from Vermont and Colorado, red, white, and black from Italy, etc.)! A travertine from Colorado lines one of the interior lobby areas. Since this is the home of Denver’s city and county court rooms, executive offices and City Council Chambers, you will have to go through a metal detector to get inside.
Wellington E. Webb Municipal Office Bldg – 201 West Colfax Avenue N39 44.419 W104 59.414
This new, 12-story, 600,000-square-foot new construction incorporates the renovated Annex One structure. One of the most striking features you will notice is the marble face sculpture at the entrance. The beautifully foliated marble is Carrera marble from Italy. The building doesn’t seem to contain any local Colorado materials, but the designers chose to expand the natural elements to the interior materials by developing the "changing of seasons" as an interiors concept. The entrance lobby has several polished and unpolished granites. The design in the granite floor is a street grid map of Civic Center. The black granite is from Zimbabwe, and is also used in the bust of Denver Mayor Wellington Webb and in the base of the exterior sculpture above. The coarse-grained greenish gray granite is the Kenoran Sage from the Forgotten Lake Quarry near Kenora, Canada. The finer-grained white/gray granite (unpolished) is Sierra White, from California. On some of the larger walls (below) in the lobby area you will see a beige oolitic limestone. Oolites are small, round or ovaloid accretions formed of calcium carbonate. The material usually develops in successive concentric layers around a nucleus such as a shell fragment or sand grain. This is a limestone from the Evans Limestone Co. in Bedford, IN, is called simply the Indiana Oolitic Limestone, and it is about 300 million years old. The elevators have a beautiful black gabbro, called Absolute Black from Zambia, Africa.
Civic Center Park - Colfax/14th and Broadway/Bannock N39 44.272 W104 59.305
In this area are the Voorhies Memorial (N) and the Greek Amphitheater (S). They are both made from light gray Turkey Creek sandstone from near Pueblo. This rock has “well-defined sedimentary structures with patterns of deposition and truncation by subsequent erosion”. Apparently, parts of the balusters (upright rail supports) in the Greek Amphitheater were replaced with Salem Limestone (same as outside the library and which contains some fossils) in the 1980s.
Denver Public Library – 14th & Broadway N39 44.245 W104 59.335
The Denver Public Library (Central) was finished in 1995 and designed by Michael Graves. The main Schlessman Hall has two nice limestones. The fine-grained tan limestone on the floor (and on some exterior walls) is from Solnhofen, near Eichstatt, Bavaria. This is referred to as Jura marble, and originated as limy mud in shallow lagoons. It contains wonderful 150-million year old fossil ammonites. (See question #1 below for logging cache.) The green limestone with it is from near Frankfurt, Germany, and contains fossil belemnites. Ammonites and belemnites were soft-bodies mollusks that lived, respectively, in coiled and chambered or bullet-shaped shells. The exterior of the library has natural and man-made stone. Along the base of the buildings and some columns is the Stony Creek Granite from New Haven County, Massachusetts. This lovely, polished granite is actually a granite gneiss, Proterozoic age, containing large orthoclase feldspar crystals, biotite and white quartz. As you look around you will see fragments of dark-colored bedrock within the gneiss! Another trim material is a fine-grained green ‘granite’, quite striking in appearance, reportedly from Austria. There is also a light gray Salem Limestone from Indiana covering parts of the exterior structure.
First Baptist Church – 14th Avenue & Grant Street N 39° 44.310 W 104° 59.030
A bit of a hike up 14th is this gorgeous American Colonial-style church especially, which stands out due to its incredible red granite columns. Polished to a high gloss, they are made from Colorado Red Granite from Pinewood Springs in Larimer. Feldspars of varying sizes make this a dramatic granite. See question #2 below to log this find. Other stone used on the exterior is Indiana Salem Limestone on the tower and trim and some pink Tennessee marble around the main entrance.
First Church of Christ, Scientist – 14th Avenue and Logan Street N39 44.309 W104 58.948
The most striking rock in this church is a unique ash flow tuff with small crystals of biotite and quartz, and grains of dark volcanic rock. The tuff, which makes up the columns and walls, represents an ancient volcanic eruption in the Oligocene of the Arkansas River Valley near Howard in Fremont County (Kerr Gulch). The building was constructed between 1901-1906. The cornerstone, laid in 1902, is made of a light gray granite with muscovite and biotite from Concord, NH, home of Mary Baker Eddy, the founder of the Christian Science church.
Colorado State Capitol – Sherman Street and East Colfax Avenue N39 44.353 W104 59.122
The exterior building material of the state capitol, including the western steps with the “ONE MILE ABOVE SEA LEVEL” notation, is a gray granite from the Aberdeen quarry in South Beaver Creek, Gunnison County. The remote location of the quarry made it difficult and expensive to transport the 280,000 cubic feet of granite to the Capitol. Don’t forget to turn around and see the magnificent view of the city and mountains here. The most famous rock in the State Capitol is the Beulah Red “marble” that covers much of the first floor interior walls and posts. All of this formation, from near Beulah in Pueblo County, was used in the capitol, and therefore can be found nowhere else on Earth. This unique rock has swirls of red, cream and gray, and is renowned for the faces and shapes it is said to hold (i.e., W.C. Fields). The rock has beautiful, iron-stained sedimentary structures and is really a very complex Mississippian limestone, not a marble or onyx. Its colors and textures are unique in the world. There is real marble on the floor of the Capitol, mostly from Vermont since the marble quarries of Colorado were closed at the time. The marble is a lovely white and gray.
To LOG this cache provide the following information to the owner:
#1: Enter the library from the west side, and shortly after, take the stairway down on the RIGHT side. turn around and look under the top lip of the first stair. Identify the distinctive ammonite (don't know what an ammonite is? See https://www.bgs.ac.uk/discoveringGeology/time/Fossilfocus/ammonite.html). There is also one near the escalator as you come in. Indicate the shape of the fossil and approximately how large it is (inches or cm). Central Library hours are: Mon-Tues : 10 a.m. - 8 p.m. Wed - Fri: 10 a.m. - 6 p.m. Sat : 9 a.m. - 5 p.m. Sun : 1 - 5 p.m. or check them at http://denverlibrary.org/locations_hours/index.html
#2: Give the range of sizes (inches or cms) of the pink feldspars (the rectangular pinkish minerals) in the columns of the First Baptist Church.
Without the answers to these queries your log will be deleted from this EC.
References: The geologic information on most of these stops comes from two sources: "Geology Tour of Denver's Buildings and Monuments" by Jack Murphy,1995, published by Historic Denver, Inc., 821 17th St., Suite 500, Denver, Colorado 80202 in cooperation with the Denver Museum of Nature and Science, 2001 Colorado Blvd., Denver, Colorado, 80205; and "Rock Around the Clock: A Geologic Walking Tour of Downtown Denver, Colorado," by Barbara J. Fillmore and Jane A. Dianich, 1992, prepared under the supervision of Peter J. Modreski, United States Geological Survey, Geologic Division.
