Welcome to my Earthcache! An Earthcache is a special type of geocache where there is no container to find - instead you are looking for a unique geological feature of the area and need to answer questions, as well as posting a picture, in order to claim the find. The goal of this Earthcache is to educate visitors about the the sediment composition and deposition processes in Smiths Mill Pond near Oakland, Ontario. Visitors will learn how sediment builds up in freshwater ponds, what gives it a “rotting” smell, and why parts of it appear to sparkle like glitter. The site highlights key concepts in sedimentology, hydrology, and glacial geology.
This earthcache will require you to paddle on Smith Mills Pond in a canoe or kayak, to the far end of the pond where there is very little water flow. You will need to bring some special equipment with you (read the questions ahead of time so you are prepared) and perform a simple science experiment. You will need a magnet, magnifying glass, and a small jar to test your sample.
EARTHCACHE REQUIREMENTS
As with all of my ECs, I am not looking for PhD thesis level responses, but I am hoping that you take some time to enjoy the area and learn something new. Please include a list of all cachers with your answer, if answering for more than one caching name, but note that each cacher must upload their own photo to their log.
This is not your typical 1.5/1.5 earthcache and you will need to complete an experiment to complete the lesson. Those who do not complete the EC as intended may have their logs deleted without notice. Please include a list of all cachers with your answer, if answering for more than one caching name, but note that each cacher must upload their own photo to their log.
To claim a 'find' for this Earthcache you must answer the following questions and send your answers in a message or email to the owner using the link at the top of the page. You can log your find with a photo at GZ. Send your answers to the tasks. I will be in contact if there is a problem, no need to wait for a response as long as the required photo is included in your log.
Questions to Answer:
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Sediment Texture & Appearance: Using your paddle or another tool of your choosing, collect a small sample of sediment and place it in a container to view it. Describe the sediment at the observation point - Is it sandy, silty, or muddy? What color is it? Do you notice anything different about the sediment here? Describe the colour, texture, etc. Now, Using a magnifying glass or a cell phone with a really good zoom, inspect the particles of the sediment more closely. Do you notice sparkling or glitter-like particles in the sediment? If so, describe the color, size, texture, structure (crystalline, cube, etc) and anything else unusual you notice about this sediment that you didn't see looking at it without magnification.
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Test for Magnetic properties: Using a magnet (a small rare earth magnet or TOTT will work fine) run the magnet through the sediment you collected. Do any of the particles stick to the magnet? Are they the same shiny particles you noted in question 1, or are they different? Describe their appearance, colour, texture, and anything else unusual you notice about them.
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Odour: Smell the sediment you collected - you might not need to hold it close to your face to get a wiff of the ofour coming from it! Describe the odor. What does this tell you about the oxygen levels and decomposition processes?
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Sediment Deposition Features: Do you see any signs of sandbars, raised areas, or sediment accumulation near the water’s edge or inflow? What do these features suggest about how sediment is moving and settling in this pond?
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Photo: Mandatory: Include a photograph of yourself, your GPS, a signature item, thumbs up, with Smiths Mills Pond included in the photograph. For bonus point, include your soil sample in the image as well! You do not need to show your face in the photo, but your photo must be unique to you. Each log must include their own photo.
(A Note from the CO: I know these are rather complex question and require you to plan ahead and bring a number of things with you to GZ. Again, given the DT rating of this cache, you're expected to make your best effort to complete the cache as intended. Anyone who does not complete the required steps may have their logs deleted without notice).
Earth Science Lesson:
Sediment Deposition and Sandbar Formation
Sediment is transported into Smiths Mill Pond through surface runoff, erosion, and small inflowing streams. As water enters the still environment of the pond, it loses velocity, which causes heavier particles like sand and gravel to settle out first, while lighter particles such as silt and clay travel further into the pond before settling. At this end of the pond there is very little flow or water movement - this contributes to the settling of particles much faster than the other end of the pond (near the mill) where the water flow is evident, and sediment does not settle as quickly due to the downward force of the water.
Over time, this process creates zones of sediment accumulation, especially near the inflow point (near the posted coordinates). These zones can build up into sandbars or sediment bars—shallow, raised areas often visible during low water conditions. Such bars indicate:
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The direction and energy of water flow
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Seasonal changes in sediment delivery
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Natural sediment sorting by particle size
In ponds like this, the sediment layers can also provide clues to past events such as flooding, erosion upstream, or land use changes nearby. Studying these patterns is important in both fluvial geomorphology (how water shapes land) and wetland ecology.
Rotting Odour and Anaerobic Conditions
Many pond visitors notice a distinctive "rotten" or sulphur-like smell when sediment is disturbed - depending on the water conditions when you visit, you're likely to notice this smell as you continue your paddle towards the far end of the pond. This is a result of anaerobic decomposition.
When organic materials like leaves, algae, or plant matter accumulate in pond sediment, they begin to break down. In deeper or stagnant areas, where oxygen is depleted, aerobic bacteria (those that need oxygen) die off and are replaced by anaerobic bacteria. These bacteria digest the organic material in the absence of oxygen, producing:
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Hydrogen sulfide (H₂S) – smells like rotten eggs
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Methane (CH₄) – odorless but contributes to the gas mix
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Ammonia (NH₃) – has a pungent, sharp smell
These gases often accumulate in soft, black organic muck and are released when the sediment is disturbed. The presence of such gases also indicates low oxygen levels (hypoxia) in parts of the pond, which can affect aquatic life by creating unsuitable conditions for fish and invertebrates.
Sparkling Sediment: Quartz, Mica, and Glacial History
One of the most visually interesting aspects of sediment in Smiths Mill Pond is its sparkling appearance, especially in bright sunlight. When you disturb the sediment, you may notice a glistening effect, like there is glitter mixed into the sediment. This glitter effect is not actually caused by glitter, but instead is caused by:
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Quartz grains – clear or milky-white particles with high light reflectivity and a crystaline structure
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Mica flakes – thin, shiny minerals that can be silvery, golden, or black, typically in flakes rather that crystals
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Magnetite - a common iron-oxide material that appears as small black crystals
These minerals are remnants of the glacial history of southern Ontario. During the last Ice Age, glaciers scraped across the Canadian Shield and deposited vast quantities of ground-up rock and sediment as they melted. This region, including Brant County, is part of the Haldimand Clay Plain, with surrounding areas containing sand and gravel outwash left by glacial meltwater.
The sparkling minerals are often deposited in ponds like this when water erodes nearby soil, carries these minerals in suspension, and slowly settles them in calm environments. Studying this glittering sediment provides insight into:
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The mineral composition of local soils and rocks
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Past glacial activity in the region
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Ongoing erosion and sedimentation processes
This cache was placed by a PROUD Platinum Earthcache Master.
