BEFORE you may log and claim this EarthCache as a find, you must first send a message or email me through my profile your answers to the following questions. Do NOT put answers in your log postings! (Answers to the questions can be found by reading the EarthCache description and reading the interpretive sign at the EarthCache coordinates.)
- What is sinter and how is it formed?
- What was a key ingredient in preserving ancient microbial life within the Excelsior Geyser Crater (read the cache description carefully)?
- Take a look around you at the posted coordinates, if you were to lead an expedition to another world looking for evidence of ancient life, what kind of life would you look for? Why? What type of geological features would you be looking for?
- Optionally post a picture of yourself and/or your GPSr at the crater.
*** All sincere efforts to answer the questions and complete the tasks will be accepted. ***
Excelsior Geyser Crater
The Excelsior Geyser Crater contains evidence of ancient microbial life buried within its layers of sinter. The process responsible for preserving this microbial life began during the last volcanic eruptions, which deposited rhyolite - a fine-grained type of volanic rock that has a high silica content.
The Excelsior Geyser, characterized by its eratic eruptions, is now a hot spring with a constant outflow of water. Over 4000 gallons of boiling water per minute pour into the Firehole River. This flowing hot water brings the silica that was left by the volcanic eruptions to the surface and deposits it there.
Microbial life
An examination of the Grand Prismatic Spring will show yellow, orange, and brown colors, which are evidence of different types of microbial life that currently live within this spring. These microbes have been living and growing here for thousands of years, building mats that line the runoff channels from the spring.
Sinter
As the Excelsior Geyser brings silica to the surface, the communities of microbes are buried alive. When these deposits of silica minerals form a crust, creating rims or terraces around the spring, it is called a sinter. New mats of microbes that grow on top of existing layers of sinter are also buried, forming additional layers of sinter.
Siliceous sediments are particularily favored for preserving evidence of life because they tend to be fine-grained and relatively stable during post-depositional changes (when they form the layer of sinter crust).
When the Excelsior Geyser erupted during the 1880s it erupted in bursts of water 50 to 300 feet high, forming the jagged crater you see today, and helping to expose the layers of sinter that had formed. Studying the perserved microbes in the layers of sinter shows the type of life that likely arose billions of years ago on our planet, when intense volcanism was widespread on the Earth.
Life on other worlds?
Evidence of preserved microbial life within layers of sinter that once lived in extreme conditions on Earth gives way to the possibility of finding similar evidence on other planets and moons where similar volcanic activity and hot spring systems produced similar living conditions.
Please be respectful of the fragile environment you are walking through. There is no need to go off the trail anywhere to complete this EarthCache.
Sources: Wikipedia, Buried Alive interpretive sign.
Placement approved by the
Yellowstone National Park