Denver Stones EarthCache EarthCache

Start: Union Station - N39 45.208 W104 59.893 - 17th & Wynkoop

Parking available here, or take the free 16th Street Mall bus down to the Wynkoop exit and walk over to 17th. The main Beaux-arts style building was built in 1918 of granite blocks after the original central structure was destroyed by fire in 1894. This granite appears to be Pikes Peak Granite, rough cut. The original north and south annexes, built in 1881, are constructed of pink and gray Castle Rock Rhyolite blocks. Rhyolite is a fine-grained igneous rock - you can see some fine crystals (phenocrysts) in the matrix that formed before the magma was extruded. Lots of gas bubbles too (vescicles). The exterior trim of the building is a pink sandstone from a quarry in Morrison, CO. Feel that it is fairly coarse-grained. Inside, the central waiting room is made of white Yule Marble, with terrazzo floors and cast iron sculpted elements. No architect is credited in any of the official information on the station. This landmark building is intrinsically tied to the growth of Denver once it became an important rail center.

Tabor Center - N39 44.925 W104 59.830 - 16th & Larimer

Unfortunately I know very little about the origins of the building stones in this stop, but they are so beautiful they are worth a look. The interior columns and some exterior trim are made of gorgeous orbicular red granite, possibly Carmen Red from Finland, and also what could be Lyons Sandstone along the bottom or the exterior walls. TASK - Measure and find the average size of the the round red/pink feldspars on the Carmen Red - you will need this to log this EarthCache. The interior has “new tile floors made of handpicked, imported stone and porcelain tile from Portugal, Pakistan, Turkey, Italy, Nigeria and Canada” (according to the Tabor Center Web site) and includes what appears to be dark somewhat orbicular gabbro(?), travertine, and some fossiliferous limestone, also seen on the exterior walls. There are really nice fossils in this limestone (see image below). In order to log the cache you will need the average size of the red round feldspars on the outside

Ghost Building - N39 44.871 W104 59.456 - 18th & Stout

The plain brown sandstone on this building is actually of an unknown source, but it has such an interesting history it is worth putting on our tour! The façade of this structure was originally at 15th and Glenarm. When the building was in disrepair and about to be destroyed, each stone was carefully removed and stored. It was incorporated into a larger office complex at its present location in 1985. The original builder, Mr. A. M. Ghost, was a local real estate broker and a member of Denver’s Psychical Research Society! It was designed by renowned architect William Lang, and is a fine example of Richardsonian Romanesque style, very popular in the late 1800s. The columns along the bottom do not appear in photos of the original building.

Boston Building – N39 44.837 W104 59.562 - 17th & Champa

This is a fine example of a building made of sandstone blocks, once very common in downtown Denver. The sandstone is from the Kemuir quarry near Manitou Springs, Colorado. Cross-bedding is easily seen in many of the blocks, formed by current deposition, and in this photo, shows that this block is upright since the tops of the beds are truncated (see this nice photo near the coffee shop door that shows sandstone layers sweeping upward to be truncated by the overlying bed - upright - Cross Bedding in Boston Building). TASK - Some blocks were placed upside down near the west side doorway – see if you can find them (See instructions for logging the cache below)! The Boston Building is in the Richardsonian Romanesque and Renaissance Revival (a cube without any projections or recessions) style. However, when the building was built, pictures show that the sandstone blocks were very rough cut - they stuck out. At some point, the blocks were sanded/smoothed flat. The flagstone in the sidewalk in front of the building is the Lyons Sandstone from north of Boulder, Colorado.

Equitable Building - N39 44.776 W104 59.582 - 17th & Stout

This building has some wonderful natural stone used all over the place and is considered one of the most elegant buildings in Denver. Originally built in 1892 in the Italian Renaissance style, it was restored in 1980. The bank on the main floor was just restored in 2002 and was made to look like a bank would when the building was originally made – it’s quite stunning. The entrance to the building has beautiful columns of Pikes Peaks Granite, and a green serpentinite, known to builders as Verde Antique (and sometimes called a marble even though it is a metamorphosed ultramafic basalt), faces the walls of the exterior north entryway (see image below). The white veins are filled with calcite (fizz it with vinegar or weak acid!). Pikes Peak granite is also on sections of the exterior, unpolished, and the granite supports the building (no steel beams). Notice the wreaths carved in the granite around the doorway - no easy task to carve granite! But inside the building is even more exciting. A fascinating Italian marble has been used on the red and white floor and stairs (and lavatory), and on the walls is a really lovely yellow onyx-like Sienna marble from France. And don’t forget to look up on the main floor. The arches are beautiful and the mosaic tile on the ceiling is completely hand-laid. The Tiffany stained-glass windows were designed specifically for this building in 1896. The capitol letter E is a theme used throughout the building, on tiles, stained glass, offices, elevators, etc. The double-faced E you also will see is the shape of the building! Upstairs is more marble, and some of statuary quality from Vermont. They sometimes have guided tours of the building on Saturdays, ask the receptionist.

Masonic Temple Building - N39 44.665 W104 59.464 -16th

The exterior of this Romanesque historic landmark a rough “Richardsonian” texture of predominantly red Permian-aged Manitou Sandstone. The sandstone was favored because it could be cut into larger blocks than the Lyons sandstone. The beautiful arch on Welton was carved in situ, one of the first examples of this in Denver. The five-story Masonic Temple was ravaged by fire in 1984, but renovators saved the building by placing a new steel frame inside the old building. The base holding up the columns (and the whole building) features the light pink, fine- to medium-grained Pikes Peak Granite, finer grained than the granite at the base of the Kittredge building next door.

Kittredge Building (Paramount Theater) - N39 44.624 W104 59.428

This historic landmark is built of two igneous rocks, rhyolite and granite. Another Richardsonian (rough-cut) Romanesque building, the Castle Rock Rhyolite (Wall Mountain Tuff) is from Douglas County, CO, and the Pikes Peak Granite (Colorado Red) is from Jefferson County, CO. TASK - Measure the average grain size of the pink feldspars in THIS granite - you will need it in order to log this EarthCache. The building was one of the first commercial structures, built in the late 1800s. Now enjoy some refreshments at the fine local establishments and take the free 16th mall bus back down toward Union Station if you parked there.

TO LOG THIS CACHE: Answer the questions:
#1. Take a picture of one of the blocks of sandstone that are upside down or tell exactly where one is (see directions above to determine if it is upside by looking at the cross-bedding).
#2.Provide the average size of the pink/red feldspars in the granite outside the Tabor Center and compare to the average size of the pink feldspars of the Pikes Peak granite in the columns of the Kittredge Building.
Email answers/photo to owner to get credit, do not post on log.

Lots of the geologic information on some 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.