The correct option is 1 and 3 only.
Explanation
Stalagmites are significant depositional landforms associated with Karst topography. They are formed by the chemical action of groundwater in limestone or dolomitic regions through the precipitation of calcium carbonate.
- Statement 1 is correct: Stalagmites form due to the dripping of mineral-rich water from the cave roof or from the tips of stalactites. When this water hits the cave floor, evaporation occurs or carbon dioxide is released, causing the calcium carbonate to precipitate and build up vertically from the ground.
- Statement 2 is incorrect: Stalagmites rise upwards from the floor of the cave. The formations that hang from the roof of the cave are called stalactites. They are often thinner at the tip and broader at the base attached to the ceiling.
- Statement 3 is correct: Stalactites grow downwards while stalagmites grow upwards. Over time, if the process continues, they may fuse together to form a continuous vertical column known as a pillar or column.
Key Takeaway: In Karst landforms, Stalactites hang from the ceiling (C for Ceiling), while Stalagmites rise from the ground (G for Ground); their union forms Pillars.