<P> The Atlas Mountains extend across much of Morocco , northern Algeria and Tunisia , are part of the fold mountain system that also runs through much of Southern Europe . They recede to the south and east , becoming a steppe landscape before meeting the Sahara desert , which covers more than 75 percent of the region . The sediments of the Sahara overlie an ancient plateau of crystalline rock , some of which is more than four billion years old . </P>
<P> The Atlas Mountains extend across much of Morocco , northern Algeria and Tunisia , are part of the fold mountain system that also runs through much of Southern Europe . They recede to the south and east , becoming a steppe landscape before meeting the Sahara desert , which covers more than 75 percent of the region . The sediments of the Sahara overlie an ancient plateau of crystalline rock , some of which is more than four billion years old . </P>
what major desert encompasses most of northern africa
what major desert encompasses most of northern africa
the Sahara desert
the Sahara desert