प्रसार केंद्रों (spreading centres) के साथ किस प्रकार की प्लेट सीमाएँ बनती हैं जहाँ विवर्तनिक प्लेटें अलग हो रही होती हैं और मेंटल से मैग्मा ऊपर की ओर धकेल कर नई क्रस्ट का निर्माण करता है?

The crescent-shaped sand dunes found in Sam, Jaisalmer are scientifically known as:

With reference to fjords, consider the following statements: I. They are deep, narrow inlets carved mainly by glaciers and later occupied by seawater. II. The shallow sill near their mouth is generally associated with glacial deposition rather than with tectonic uplift alone. III. They are chiefly associated with high-latitude or formerly glaciated coasts, rather than with humid tropical landscapes. How many of the statements given above are correct?