In arid and semi arid geomorphology, a landform developed mainly by deposition toward the centre of an intermontane basin, often forming a flat dry lake bed, is known as what?

Introduction / Context:
Desert and semi arid landscapes have distinctive erosional and depositional landforms. Intermontane basins, which are low areas between mountain ranges, often collect sediment and water from surrounding highlands. Over time, specific features such as pediments, bajadas, and playas develop. This question asks you to identify the depositional landform that forms in the centre of these basins and is often visible as a flat, dry lake bed.

Given Data / Assumptions:

• The setting is an intermontane basin in an arid or semi arid region.
• Deposition occurs toward the centre of the basin.
• The resulting landform is a flat central feature, often associated with ephemeral lakes.
• Options include pediment, bajada, playa, and peneplain.

Concept / Approach:
A playa is a flat bottomed depression at the lowest part of an internally drained basin, which may temporarily hold water after rain but is often dry and covered with fine sediments or salt deposits. Pediments are gently sloping rock surfaces at the foot of mountains; bajadas are coalesced alluvial fans along the basin margin; and peneplains are near level erosion surfaces formed over very long time scales. Because the question emphasises deposition toward the centre of an intermontane basin, the correct landform is playa.

Step-by-Step Solution:
Step 1: Identify that the landform is depositional and forms in the centre of a basin, not on its margins. Step 2: Recall that playas are central basin floors where fine sediments and dissolved minerals accumulate after runoff from surrounding highlands. Step 3: Pediments develop as gently inclined rocky surfaces at the foot of mountains, mainly through erosion rather than central deposition. Step 4: Bajadas are belts formed by overlapping alluvial fans along the mountain fronts, still near the basin margin, not in its centre. Step 5: Peneplains are generalized low relief erosion surfaces that can form in many climatic settings, not a specific feature of intermontane desert basins. Step 6: The description of a central depositional flat in an arid basin fits the definition of a playa.

Verification / Alternative check:
Desert geomorphology diagrams show a typical sequence from mountains to basin centre: steep slopes, pediments, alluvial fans, bajada belts, and finally a central playa. Playa surfaces can be mud flats, salt pans, or ephemeral lake beds that fill briefly after storms. These features are collectively referred to as playas in geographic literature, confirming that playa is the correct technical term matching the question description.

Why Other Options Are Wrong:

• Pediment: An erosional slope at the foot of a mountain, not a central basin deposit.
• Bajada: A merged zone of alluvial fans along the basin margins, not the lowest central part.
• Peneplain: A broad, almost level erosion surface over a wide region, not specifically tied to intermontane basins in arid climates.

Common Pitfalls:
Because pediments, bajadas, and playas often appear together in diagrams, students sometimes confuse their positions. A useful rule is to visualise a cross section: mountain front, pediment, alluvial fans, bajada belt, and then a central playa. Remember that playa represents the flat lowest point where water and fine sediments concentrate, while pediments and bajadas are closer to the mountain edges.

Final Answer:
The depositional landform toward the centre of an intermontane basin in arid regions is a playa.