Karewas are lacustrine (lake) deposits found in the Kashmir Valley and surrounding areas. The term 'Karewa' originates from the Kashmiri word meaning ‘elevated ground’. These formations are crucial for understanding the geological history of the Himalayas and are economically significant due to their alluvial deposits, particularly for agriculture and building materials. The Karewa Group represents a period of significant tectonic activity and climate change in the region, providing valuable insights into the evolution of the landscape and paleoenvironmental conditions. Their study is vital for hazard assessment and resource management in the region. Formation and Geological Setting The Karewa Group’s formation is linked to the Pleistocene epoch, specifically during the period of glacial and interglacial cycles. The formation process can be summarized as follows: Tectonic Activity: Uplift of the Pir Panjal range led to the creation of a basin. Lake Formation: The uplift blocked the drainage of the region, resulting in the formation of a large lake known as the ancient Lake Karewa. Sedimentation: Sediments eroded from the surrounding mountains (Himalayas and Pir Panjal) were deposited into the lake. These sediments included glacial outwash, fluvial deposits, and lacustrine sediments. Regression and Uplift: Over time, the lake regressed due to sedimentation and tectonic uplift, leaving behind the Karewa deposits as terraces and plateaus. Lithology and Stratigraphy The Karewa Group is characterized by a sequence of unconsolidated sediments. The lithology varies depending on the depositional environment, but generally includes: Gravels: Coarse-grained sediments deposited by glacial meltwater streams. Sands: Medium-grained sediments representing fluvial and deltaic environments. Silts and Clays: Fine-grained sediments deposited in quieter lacustrine conditions. Loess: Wind-blown silt deposits, often found overlying the Karewa sediments. Paleosols: Ancient soil horizons indicating periods of landscape stability. The Karewa Group is typically divided into three main formations: Lower Karewa: Characterized by coarse conglomerates and gravels. Middle Karewa: Predominantly composed of sands and silts, representing the main lacustrine phase. Upper Karewa: Consists of fine-grained sediments, loess, and paleosols, indicating a transition to drier conditions. Distribution and Extent The Karewa deposits are primarily found in the Kashmir Valley, extending from Baramulla in the northwest to Shopian in the south. They are also found in the surrounding areas, including: Wular Lake Basin: Significant Karewa deposits are present around the Wular Lake. Budgam and Pulwama Districts: These districts contain extensive Karewa terraces used for agriculture. Poonch and Rajouri Districts: Smaller Karewa formations are found in these regions. Economic Significance The Karewa Group holds significant economic importance for the following reasons: Agriculture: The fertile Karewa soils are ideal for growing saffron, walnuts, apples, and other crops. The Karewa lands constitute a significant portion of the agricultural land in Kashmir. Building Materials: The gravel and sand deposits are used extensively in construction. Water Resources: The porous nature of the Karewa sediments makes them important groundwater reservoirs. Paleoclimate Reconstruction: The sediments provide valuable information about past climate changes and environmental conditions. Archaeological Significance: Karewa sites have yielded archaeological artifacts, providing insights into the region’s past human settlements. Geohazards Karewa deposits are prone to certain geohazards: Landslides: The unconsolidated nature of the sediments makes them susceptible to landslides, especially during heavy rainfall. Flooding: The low-lying Karewa areas are vulnerable to flooding from rivers and streams. Seismic Vulnerability: The region is seismically active, and the Karewa sediments can amplify ground shaking during earthquakes. The Karewa Group represents a unique geological formation with significant implications for understanding the Himalayan landscape evolution, paleoenvironmental conditions, and economic resources of the Kashmir Valley. Its fertile soils support agriculture, while its sediments provide valuable building materials and groundwater resources. However, the inherent geohazards associated with these deposits necessitate careful land-use planning and mitigation strategies to ensure sustainable development and minimize risks to the local population. Further research into the Karewa Group’s stratigraphy and geomorphology is crucial for effective resource management and disaster preparedness.

Karewa Group | UPSC Mains GEOLOGY-PAPER-I 2018

Karewa Group

How to Approach

This question requires a detailed understanding of the Karewa Group, its geological significance, formation, and economic importance. The answer should cover its location, lithology, age, and the resources it holds. A structured approach involving defining Karewas, explaining their formation, detailing their geological characteristics, discussing their economic significance, and mentioning their distribution is crucial. Focus on the unique features that distinguish Karewas from other sedimentary formations.

Formation and Geological Setting

The Karewa Group’s formation is linked to the Pleistocene epoch, specifically during the period of glacial and interglacial cycles. The formation process can be summarized as follows:

Tectonic Activity: Uplift of the Pir Panjal range led to the creation of a basin.
Lake Formation: The uplift blocked the drainage of the region, resulting in the formation of a large lake known as the ancient Lake Karewa.
Sedimentation: Sediments eroded from the surrounding mountains (Himalayas and Pir Panjal) were deposited into the lake. These sediments included glacial outwash, fluvial deposits, and lacustrine sediments.
Regression and Uplift: Over time, the lake regressed due to sedimentation and tectonic uplift, leaving behind the Karewa deposits as terraces and plateaus.

Lithology and Stratigraphy

The Karewa Group is characterized by a sequence of unconsolidated sediments. The lithology varies depending on the depositional environment, but generally includes:

Gravels: Coarse-grained sediments deposited by glacial meltwater streams.
Sands: Medium-grained sediments representing fluvial and deltaic environments.
Silts and Clays: Fine-grained sediments deposited in quieter lacustrine conditions.
Loess: Wind-blown silt deposits, often found overlying the Karewa sediments.
Paleosols: Ancient soil horizons indicating periods of landscape stability.

The Karewa Group is typically divided into three main formations:

Lower Karewa: Characterized by coarse conglomerates and gravels.
Middle Karewa: Predominantly composed of sands and silts, representing the main lacustrine phase.
Upper Karewa: Consists of fine-grained sediments, loess, and paleosols, indicating a transition to drier conditions.

Distribution and Extent

The Karewa deposits are primarily found in the Kashmir Valley, extending from Baramulla in the northwest to Shopian in the south. They are also found in the surrounding areas, including:

Wular Lake Basin: Significant Karewa deposits are present around the Wular Lake.
Budgam and Pulwama Districts: These districts contain extensive Karewa terraces used for agriculture.
Poonch and Rajouri Districts: Smaller Karewa formations are found in these regions.

Economic Significance

The Karewa Group holds significant economic importance for the following reasons:

Agriculture: The fertile Karewa soils are ideal for growing saffron, walnuts, apples, and other crops. The Karewa lands constitute a significant portion of the agricultural land in Kashmir.
Building Materials: The gravel and sand deposits are used extensively in construction.
Water Resources: The porous nature of the Karewa sediments makes them important groundwater reservoirs.
Paleoclimate Reconstruction: The sediments provide valuable information about past climate changes and environmental conditions.
Archaeological Significance: Karewa sites have yielded archaeological artifacts, providing insights into the region’s past human settlements.

Geohazards

Karewa deposits are prone to certain geohazards:

Landslides: The unconsolidated nature of the sediments makes them susceptible to landslides, especially during heavy rainfall.
Flooding: The low-lying Karewa areas are vulnerable to flooding from rivers and streams.
Seismic Vulnerability: The region is seismically active, and the Karewa sediments can amplify ground shaking during earthquakes.

Additional Resources

Key Definitions

Lacustrine

Relating to or living in lakes.

Pleistocene Epoch

A geological epoch that lasted from about 2.58 million to 11,700 years ago, characterized by repeated glacial cycles.

Key Statistics

Approximately 70% of the agricultural land in the Kashmir Valley is located on Karewa deposits (Source: Department of Agriculture, Kashmir - Knowledge cutoff 2023).

Source: Department of Agriculture, Kashmir

The Kashmir Valley receives an average annual rainfall of 1000-1500 mm, contributing to the instability of Karewa slopes (Source: India Meteorological Department - Knowledge cutoff 2023).

Source: India Meteorological Department

Examples

Saffron Cultivation

The Karewa lands of Pampore in Kashmir are renowned for saffron cultivation, which thrives in the well-drained, fertile soils of the Karewa deposits. Pampore is often referred to as the "Saffron Town of Kashmir".

Wular Lake and Karewa Interaction

The Wular Lake, one of the largest freshwater lakes in Asia, is directly influenced by the Karewa deposits. Sedimentation from the surrounding Karewa formations contributes to the lake's dynamic ecosystem and influences its water quality.

Frequently Asked Questions

▶What is the primary cause of landslides in Karewa areas?

The primary cause of landslides in Karewa areas is the unconsolidated nature of the sediments, combined with heavy rainfall, seismic activity, and human interference such as deforestation and construction.