<
Hundreds of millions of years would pass before something capable of self replication would emerge from the primordial soup. These early organisms known as cyanobacteria, or blue-green algae were simple unicellular organisms that used energy from the sun to grow. They were critical to the evolution of all other life as they produced, via photosynthesis, the oxygen required to support later more complex organisms on Earth.
Whilst descendants of these early microorganisms are still with us today, periodically cropping up in my marine fish tank, they are also very very occasionally to be found preserved in the fossil record. Their rarity is due to the great length of time the fossils have had to survive - up to 3.5 billion years in some cases. Countless continental plate subductions, volcanic events, deposits of sediment as well as numerous glaciations have destroyed or buried these most ancient of fossils.
There are two main types of cyanobacterial fossil deposits, stromatolites and thrombolites. They range in age between 3500 000 000 and 650 000 000 years old. Stromatolites are by far the most common. They consist of many laminar layers of algal mats and are frequently found inside limestone cave systems where they are protected from most geomorphological events. Thrombolites are much much much less common. In fact the best examples have been found at just three sites; two in Western Australia and the third right here at Flower's Cove, Newfoundland. The Australian specimens are more numerous, but for sheer size you cant beat the thrombolites of Newfoundland.
Thrombolites differ from stromatolites in that they have a clotted internal structure as opposed to the ordered layering of stromatolites. These clots each represent a single original cyanobacterial colony and were formed by the calcification of the algal colonies in the warm shallow seas of the early Earth. Later (ie younger) thrombolites also tend to have burrowing or boring tunnels within them made by early metazoan creatures that coexisted with them.
The thrombolites of Flowers Cove are just 500 meters from the waypointed parking at the trailhead. There are two sites on the trail that you will need to visit. Please email me the answers to the Logging Requirements via my profile page. If you have any concerns about your answers, an optional photograph of your group at GZ is a great way to show me you were there. Dont stress about your answers, they can mostly be found on the infomation board at GZ. Enjoy !
Logging Requirements
At waypoint 1
1. what is the diameter and height of the largest thrombolite ?
2. describe the colour and surface texture of this thrombolite ? According to the cache page, would you consider these to be younger or older specimens of thrombolites ?
At the posted coordinates, find the information board.
3. Are these structures considered true fossils ?
4. How did the darker rocks get here ?
5. What is the purpose of the furrows on the thrombolites ?
6. where in Western Australia can the other thrombolites be found ?
Congratulations to mnloon on the FTF !