The question asks about the main processes involved in landscape formation due to running water. We need to identify the three primary geomorphic processes associated with fluvial (river) action.
Correct Option: C) Erosion, transportation, and deposition
These three processes – erosion, transportation, and deposition – are the fundamental ways in which running water modifies and shapes landscapes. They represent a complete cycle of material removal, movement, and eventual settling.
The question asks for the geological term that describes the lowest level to which a river can erode its bed. This concept is fundamental in fluvial geomorphology, defining the ultimate limit of downward erosion by a stream.
Correct Option: C) Base level is the lowest level to which a river can erode its bed. This is the theoretical limit for stream erosion, often represented by sea level, but can also be a local base level like a lake or a resistant rock layer.
The concept of a "graded river" is fundamental in geomorphology, referring to a river that has reached a state of equilibrium. Understanding this equilibrium involves considering the balance between erosion, transport, and deposition of sediment by the river's flow.
A) Has achieved dynamic equilibrium — gradient just sufficient to transport sediment supplied without net erosion or deposition. This definition perfectly encapsulates the concept of a graded river. It highlights the balance between sediment supply and transport, leading to a stable channel over time, characterized by a specific gradient.
The question asks about the typical long profile of a river. The long profile refers to the gradient of the river bed from its source to its mouth. We need to understand how the slope of a river changes along its course due to erosional and depositional processes.
Correct Option: C) Concave upward — steep near source, gentle near mouth
This option accurately describes the typical long profile of a river. The river's gradient is highest in its upper course (near the source) where it has significant erosional power, and it gradually decreases, becoming very gentle in its lower course (near the mouth) where deposition is the dominant process. This creates a concave upward curve.
The question asks to identify the process of river erosion known as "corrosion (solution)". This requires understanding the different types of river erosion and their specific mechanisms.
Correct Option: C) River water chemically dissolving soluble rock minerals
The question asks about the process of "saltation" in river transport. This term refers to a specific mechanism by which sediments are moved by flowing water. Understanding the different modes of sediment transport is key to answering this question.
B) Bouncing along the riverbed in a leaping motion. This accurately describes saltation, where particles are intermittently lifted by the current and then fall back, creating a series of hops or leaps along the bed.