William Henry Seward Monument EarthCache

The listed coordinates will bring you to the William Henry Seward Monument in downtown Anchorage, Alaska. William Henry Seward was a prominent American statesman known for negotiating the purchase of Alaska from Russia in 1867. His efforts expanded the U.S. territory significantly and brought valuable natural resources to the nation. As Secretary of State during the Civil War, he skillfully navigated international relations, securing European neutrality and contributing to the Union's victory. Seward's legacy endures as a key figure in American history, celebrated for his diplomatic acumen and significant contributions to territorial expansion.

The William Henry Seward Monument was constructed from Alaskan marble, which was likely quarried in southeast Alaska. The geological journey of Alaskan marble begins with the deposition of calcium rich marine sediments in ancient seas that once covered parts of what is now Alaska. Over time, these sediments accumulated in layers, and as the seas receded, the accumulated materials were buried deep within the Earth's crust. As the buried sediment layers experienced increasing pressure and heat from the Earth's interior, a process known as metamorphism took place. Metamorphism involves the recrystallization of minerals, transforming the original limestone into the exquisite marble seen today. The heat and pressure caused the limestone's mineral structure to undergo significant changes, resulting in the development of the characteristic interlocking calcite crystals found in marble.

What sets Alaskan marble apart from other marble varieties is its unique and stunning veining patterns. These striking patterns are a result of impurities present in the original limestone, such as clay, silt, and various minerals. The heat and pressure of metamorphism caused these impurities to recrystallize differently from the surrounding calcite, forming intricate patterns of contrasting colors and textures. The colors of Alaskan marble can vary widely, ranging from pure white to shades of gray, green, blue, and even pink. These hues are influenced by the types of impurities present during the metamorphic process. For instance, the presence of serpentine minerals can give Alaskan marble a greenish hue, while hematite impurities may contribute to pink or reddish tones. Graphite or pyrite can introduce shades of gray or black to the marble, creating darker-colored varieties that add depth and contrast to the stone. When limonite is present, Alaskan marble may display yellowish or brownish colors, bringing earthy tones to the stone. Or when dolomite is present in the original limestone, it can result in variations of beige or cream colors in the marble. It's important to note that the specific combination and concentration of these impurities and minerals, as well as the conditions of metamorphism, influence the exact color and veining patterns observed in different Alaskan marble deposits.

1. Describe the color, texture, and grain size of the marble. Is the surface smooth, or rough?
2. Describe the veining within the rock. Do the veins run in a particular direction, or does it appear "random"?
3. What mineral do you think is primarly responsible for giving this marble its color?
4. Upload a photo with the William Henry Seward Monument. You don't have to be in the photo, though it is strongly encouraged.