The Thar region forms part of the bigger desert of the same name that sprawls over a vast area of Pakistan and India from Cholistan to Nagar Parkar in Pakistan and from the south of Haryana down to Rajisthan in India.
The district is mostly desert and consist of barren tracts of sand dunes covered with thorny bushes. The ridges are irregular and roughly parallel, that they often enclosed sheltered valleys, above which they rise to a height of some forty six meters. These valleys are moist enough to admit cultivation and when not cultivated they yield luxuriant crops of rank grass. But the extraordinary salinity of the subsoil and consequent shortage of potable water, renders many tracts quite uninhabitable. In many of the valleys the subsoil water collects and forms large and picturesque salt lakes, which rarely dry up.
The only hills in the district are at Nagarparkar on the northern edge of the Rann of Kutch which belongs to quite a different geological series. It consist of granite rocks, probably an outlying mass of the crystalline rocks of the Aravalli range. The Aravalli series belongs to Archaen system which constitutes the oldest rocks of the earth crust. This is a small area quite different from the desert. The tract is flat and level except close to Nargarparkar itself. The principal range Karunjhir is 19 kilometers in length and attains a height of 305 meters. Smaller hills rise in the east, which are covered with sparse jungle and pasturage and give rise to two perennial springs named Achleshwar and Sardharo as well as temporary streams called Bhetiani and Gordhro, after the rains.
On the south of the district is the great Rann an immense sart water. It
is a flat land, almost at sea level. covered with thick layer of salt which
has been left by evaporation of sea water over the centuries. During monsoon
it becomes almost part of the sea owing to influx of sea water at Lakhpat
Bander on Kori mouth of the Indus and other places. During winter it mostly
dries up and surface is covered with salt. At places where the land rise up
by few meters, it becomes an island and thus called "bet".