What must be present on a rock that undergoes frost wedging
holes around it
sharp edges
a crack
round shape
A crack must be present on a rock that undergoes frost wedging. Frost wedging occurs when water seeps into the cracks and freezes, expanding and causing the crack to widen. Holes around it, sharp edges, or a round shape are not necessarily required for frost wedging to occur.
what is the very last stage of physical weathering in rocks
pebbles
sand
The very last stage of physical weathering in rocks is the formation of sand. Over time, as rocks undergo various physical weathering processes such as frost wedging, pressure release, or abrasion, they gradually break down into smaller pieces. These smaller pieces eventually become sand particles.
To undergo frost wedging, a rock must typically have the following features:
1. Water: Frost wedging most commonly occurs in environments with freezing temperatures and the presence of water. Water can seep into cracks and pores of the rock.
2. Cracks or Joints: The presence of cracks or joints is necessary for water to penetrate into the rock. These cracks might already be present in the rock due to geological processes or human activity.
3. Porosity: Rocks with porosity, meaning they have interconnected pore spaces or openings, are more prone to frost wedging. This is because water can infiltrate into the rock and expand when it freezes.
4. Freezing and Thawing Cycles: Please note that the presence of freezing and thawing cycles is required rather than a specific shape or feature of the rock. The expansion of water as it freezes and contracts as it thaws exerts internal pressure on the rock, leading to the mechanical breakdown over time. This process is known as frost wedging.
Therefore, the specific features you mentioned, such around the rock, sharp edges, or a round shape, do not necessarily have to be present for frost wedging to occur. The primary factors are the presence of water, cracks or joints, porosity, and the occurrence of freezing and thawing cycles.
To understand what must be present on a rock that undergoes frost wedging, let's first explain what frost wedging is. Frost wedging is a type of physical weathering that occurs when water fills cracks or pores in rocks, and then freezes and expands, causing the rock to break apart.
Now, based on this process, there are a few characteristics that must be present for frost wedging to occur:
1. Presence of Water: Frost wedging requires the presence of water in the cracks or pores of the rock. This water can come from rain, snow, or ice melt. Without water, frost wedging cannot happen.
2. Cracks or Pores: The rock must have cracks or pores for water to accumulate. These cracks can be natural, such as joints or bedding planes, or they can result from previous weathering processes. The presence of cracks or porous spaces allows water to seep in and accumulate.
So, among the options you provided:
- "Holes around it" would suggest the presence of cracks or pores where water can accumulate, which is a characteristic seen in rocks undergoing frost wedging.
- "Sharp edges" or a "round shape" are not directly related to frost wedging. The shape of the rock does not determine if frost wedging occurs or not. However, sharp edges may be formed as a result of the rock breaking apart due to frost wedging.
To summarize, for a rock to undergo frost wedging, it needs to have cracks or pores that can hold water. The presence of "holes around it" suggests the potential for water accumulation, making it more likely for frost wedging to occur.