The Cretaceous System is a series of stratified rocks that typically lay above the Jurassic system and below the oldest Tertiary deposits; hence, the closing records of the vast Mesozoic epoch may be found in this system. The name is an outstanding example of the inconvenient nature of using a local lithological characteristic in the descriptive term of a broad rock system. This article will explain to you about the Cretaceous System which will be helpful in Geography preparation for the UPSC Civil service exam.

Cretaceous Period

• In geologic time, the Cretaceous Period is the final of the Mesozoic Era's three eras.
• The Cretaceous Period began 145.0 million years ago and ended 66 million years later; it came after the Jurassic Period and was replaced by the Paleogene Period.
• The Cretaceous Period is the longest of the Phanerozoic Eon.
• It spans 79 million years, which is more time than has passed since the extinction of the dinosaurs at the conclusion of the era.
• The majority of Cretaceous rocks are not chalked, but the majority of chalks were deposited during the Cretaceous period.
• They have not been distorted or eroded and are relatively close to the surface, many of these rocks reveal distinct and easily accessible characteristics of the time, as seen in the white cliffs surrounding the Strait of Dover between France and England.

Cretaceous System

• The Deccan trap or Cretaceous Rock Structure is generated by the passage of magma in layers over the cemented rock system.
• The Cretaceous period is well represented in India by a variety of characteristics, including magmatic, volcanic, and sedimentary rocks that are extensively spread in the peninsular shield as well as limited to narrow linear bands in the Himalayas
• The Rajmahal Traps on the eastern boundary of the Indian plate and the Deccan Traps outcropping in the western and central parts of the Indian shield constitutes a remarkable geological landmark in the Indian shield's geodynamic history.
• Volcanic outbursts over a large area of Peninsular India caused the Deccan trap to rise from the end of the Cretaceous to the beginning of the Eocene.
• The term "trap" means "stair" or "step" in Swedish, and it was given this name owing to the deposition of the volcanic eruption, which has a flat top and steep sides.
• Weathering and denudation have decreased the size of the Deccan trap to around half its initial extent.
• Coal is one of the most important products of this system's rocks.
• Cretaceous series fossils include marine, fresh-water, and terrestrial animals and plants.

Cretaceous System - Formation

• As India moved northwards, the Cretaceous Period saw numerous dramatic changes in basinal configurations as a result of the closure of the ancient rift (Gondwanan) basins and the creation of new extensional structures and marginal down warpings.
• Diverse tectonic sedimentary settings range from active margins in a subduction zone-island arc collisional framework operating along the northern (Himalayan) and eastern (Arakan-Yoma) boundaries.
• Extending to the Andaman-Nicobar island complex; transgressions followed along reactivated rifts with the gradual spreading of epicontinental seas in downward areas including continental plate margins.
• The formation and preservation of a regolith providing dinosaur nests atop the shield basement and coated by the Deccan lava flows are one of the most stunning characteristics of the Indian Cretaceous.

Cretaceous System - India

• Sandstones, quartzites, limestones, and shales are among the Cretaceous rocks found in the Spiti region.
• Sandstones and shales are prominent rocks in the Kumaon area.
• Cretaceous limestones may also be found in Kashmir's Rupshu and Burzil districts. Sandstones may be found on the Meghalaya plateau.
• The Pondicherry-Tiruchchirapalli belt contains the upper Cretaceous system. Some disconnected marine Cretaceous outcrops called Bagh Beds near Gwalior may be found along the Narmada Valley, underpinning the Deccan Trap.
• The Lemetas are estuarine and lacustrine deposits found in the Peninsula's central region.
• Divide India's geographical land area into three parts: Deccan trap, Gondwana, and Vindhyan.
• The Deccan Trap affects practically all of Maharashtra, as well as sections of Gujarat, Karnataka, Madhya Pradesh, and, to a lesser extent, Andhra Pradesh.
• The Deccan Trap is assumed to have originated during the Mesozoic epoch as a result of subaerial volcanic activity connected with continental divergence in this section of the Earth.

The Deccan Trap

• Volcanic activity in peninsular India began during the Mesozoic era's last stage (Cretaceous period).
• As a result of the fissure eruption, the Deccan trap was developed.
• The rocks used to build this building include basalt and dolerite.
• Due to these rocks being extremely hard, weathering has resulted in the creation of black soil.
• This construction may be found across the majority of Maharashtra, as well as sections of Gujarat, Madhya Pradesh, and Tamil Nadu.
• The thickness of the Deccan Traps is 3,000 meters along the west, 600-800 meters to the south, 800 meters in Kachchh, and just 150 meters to the east.
• Long-term weathering of these rocks has resulted in the formation of black cotton soil known as regur.

Conclusion

The Cretaceous System is a succession of stratified rocks that normally lie above the Jurassic system and below the earliest Tertiary deposits; hence, the Cretaceous System may contain the last records of the enormous Mesozoic epoch. The transit of magma in layers across the cemented rock structure creates the Deccan trap or Cretaceous Rock Structure. In India, the Cretaceous epoch is well characterized by a range of features such as magmatic, volcanic, and sedimentary rocks.

FAQs

Question. What is the Cretaceous System?

Question. What are the major characteristics of the Cretaceous period?

Question. What are the significant events during the Cretaceous period?

Question. What is the importance of the Cretaceous period in the context of Earth’s geological history?

Question. What fossil evidence is associated with the Cretaceous period?

MCQs

1. Which of the following is true about the Cretaceous period?

A) It is part of the Paleozoic Era.

B) It saw the dominance of dinosaurs.

C) It ended approximately 100 million years ago.

D) It was characterized by the dominance of mammals.

2. When did the Cretaceous period occur?

A) 300-250 million years ago

B) 145-66 million years ago

C) 66-50 million years ago

D) 50-25 million years ago

3. What was a major geological event during the Cretaceous period?

A) The Ice Age

B) The breakup of the supercontinent Pangaea

C) The formation of the Himalayas

D) The eruption of Mount Vesuvius

4. What type of plants emerged during the Cretaceous period?

A) Mosses

B) Gymnosperms

C) Angiosperms (flowering plants)

D) Ferns

5. What was the fate of dinosaurs at the end of the Cretaceous period?

A) They evolved into mammals

B) They migrated to other continents

C) They went extinct

D) They became marine reptiles

GS Mains Questions and Model Answers

Q1. Explain the significance of the Cretaceous period in the context of biological evolution.

Answer: The Cretaceous period was significant in biological evolution as it marked the peak of dinosaur dominance, along with the emergence of flowering plants (angiosperms). This period witnessed a diversification of both plant and animal life, with new species of dinosaurs, marine reptiles, and early birds. The development of angiosperms also had a profound effect on plant-pollinator relationships, which influenced ecological systems for millions of years. The end of the Cretaceous saw one of the largest mass extinctions in Earth’s history, which radically altered the evolutionary course of life, paving the way for the rise of mammals.

Q2. Discuss the major geological developments during the Cretaceous period and their impact on the Earth’s surface.

Answer: The Cretaceous period saw significant geological developments, particularly the rifting and drifting of continents, which led to the separation of the supercontinent Pangaea. This breakup resulted in the formation of new oceanic and continental landmasses, which contributed to the Earth’s current configuration. The period also experienced extensive volcanic activity, which contributed to the creation of new crust and the shaping of ocean basins. These geological changes had a lasting impact on the Earth’s surface, influencing climate patterns, ocean currents, and the distribution of species.

Q3. Analyze the relationship between the Cretaceous period and the extinction event that ended it.

Answer: The Cretaceous period ended approximately 66 million years ago with one of the most significant mass extinction events in Earth’s history. This event, which is widely believed to have been caused by an asteroid impact, led to the extinction of nearly 75% of all species, including the non-avian dinosaurs. This extinction paved the way for the rise of mammals and the eventual dominance of humans. The effects of the extinction event were felt across the planet, as it caused massive climate changes, including a "nuclear winter" effect, with dust and debris blocking sunlight and disrupting ecosystems.

Previous Year Questions on  Cretaceous System

1. UPSC CSE 2023

Question: "Describe the major biological and geological events during the Cretaceous period."

Answer: The Cretaceous period was marked by the dominance of dinosaurs and the emergence of flowering plants (angiosperms). It was also a time of significant geological activity, including the breakup of the supercontinent Pangaea and the formation of new continents and oceanic basins. This period ended with a mass extinction event that wiped out many species, including the non-avian dinosaurs.

2. UPSC CSE 2022

Question: "How did the Cretaceous period contribute to the evolution of modern flora and fauna?"

Answer: The Cretaceous period contributed significantly to the evolution of modern flora and fauna through the emergence of angiosperms (flowering plants) and the diversification of dinosaurs, including the early ancestors of birds. The period also saw the rise of mammals, although