They are spread across Haryana, Rajasthan, Gujarat, and Delhi, over a total of 692 kilometre (km).
There are divided into two main ranges, Sambhar Sirohi Range and the Sambhar Khetri Range.
They are fold mountains formed in a convergent plate boundary.
For mains
The significance of Aravalis
They act as a barrier between the fertile plains of Punjab and Haryana and the western desert (Thar).
They provide home to over 300 indigenous plant species and over 120 bird species and a range of endemic animal species.
They also help divert monsoon to the Sub Himalayan region which helps in the formation of multiple river systems in northern India.
What are the concerns
Illegal quarrying has resulted in the loss of a large portion of the hill ranges along with its forest cover.
The quarrying in the hill ranges increases the pollution caused by particulate matter (PM 10 and PM 2.5) in the Delhi NCR region.
The drainage pattern in the region has been altered resulting in the death of a number if rivers and their tributaries.
The loss of forested land has resulted in increasing conflict between man and animal as well as loss of the natural habitat of a large number of species.
Why illegal mining is continuing
The main reason can be said to be a lack of political will.
Another reason cited is the overlapping of jurisdictions due to the large area covered by the ranges as well as lack of clearcut demarcation in the region.