Some Details of the Creation of this Universe Here

Allah denounces the idolators who worship other gods apart from Him although He is the Creator, Subduer and Controller of all things. He says:

قُلْ أَءِنَّكُمْ لَتَكْفُرُونَ بِالَّذِى خَلَقَ الاٌّرْضَ فِى يَوْمَيْنِ وَتَجْعَلُونَ لَهُ أَندَاداً

it is stated separately: وَجَعَلَ فِيهَا رَ‌وَاسِيَ مِن فَوْقِهَا وَبَارَ‌كَ فِيهَا وَقَدَّرَ‌ فِيهَا أَقْوَاتَهَا فِي أَرْ‌بَعَةِ (He has placed firm mountains in it [ the earth ] towering above it, and put blessings in it, and proportioned its foods therein, in four days - 10). It should be remembered that the four days mentioned in this verse are inclusive of the first two days mentioned in verse 9, according to the consensus of the exegetes. The first two days and the later four days are not separate, otherwise the total period of creation would become eight days which is against the explicit statement of the Qur'an.

It appears that it would have been more proper at this point if, after mentioning the creation of earth in two days, the creation of mountains etc. were also mentioned in two days, and thus it would have been known that the total number of days taken for the creation of earth was four. But by choosing to state that the number of days including the remainder of the earth's creations totals four, Qur'an has probably indicated that the four days were not continuous, but in two parts - two days before the creation of the skies, and two days after it. The creation of mountains etc. mentioned in the verse 10, relates to the period after the creation of the skies. And Allah knows best.