You will be looking for a group of two rocks along the walking trail. The last rock is the one you will be looking at.
Ichnofossils is just a fancy term for trace fossils found in the rocks. The original sedimentary deposits were altered after depostion by living oganisms. The activity by the animal is preserved in the stone, but didn't preserve the plant or animal. This is different from body fossils which fossilize the remains of the oganism. So what are the different kinds of ichnofossils?
Common ichnofossils are footprints, burrows, borings, feeding marks, and root cavities. Footprints are obviously the tracks made by the animal when moving across the ground. Burrows are tunnels or holes dug out by animals to create a space for habitation. Borings are carved into solid rock and would have serrated edges. Feeding marks are what you think they are: marks left behind by teeth.
So how did the fossils get there? Most trace fossils are formed in soft mud or sand. The imprints became covered by sediment and dried hard. This had to be done quickly so the imprints were not removed by water or wind. As this process of sedimentation continues, the new sediment and layers will compact and cement together to form the rock that you see today.
Speaking of today, you are now looking at a sediementary rock (limestone) that was brought in when the trail was created. You should be looking at a rock that has been discolored by mineral deposits in the limestone. Iron would be red color, black color would be organic carbon, calcite would be white,
Send me your answers to the following questions:
1. Identify the type of ichnofossil on this limestone.
2. Describe in your own words how this fossil formed.
3. Are the fossils you see uniform in size or are they different?
4. What mineral do you think changed the color of the limestone? Do you think it came from the same source as the rock next to it?
5. Post a picture of yourself (face not required) or a personal item. Please do not post spoiler pictures.
sources: wikipedia, american geosciences institute