The phrase "formidable mountains" is grammatically correct and usable in written English.
It is generally used to describe mountains that are imposing, impressive, or intimidating in size, shape, or appearance. Example: "As we trekked through the dense forest, we were suddenly met with the sight of formidable mountains rising up in the distance, their snow-capped peaks reaching towards the sky."
Next year, for the very first time, the Tour will send cyclists up a formidable mountain on the final Saturday, the last day of real competition.
With his brooding eyes, flowing dark hair and a voice inflected with the rumble and drawl of his native Denmark, he's a formidable mountain of a man.
Difficult to reach because of this formidable mountain, Cadaqués has long been popular with artists and an offbeat, bohemian European crowd.
The inclusion of countries such as Spain and Italy, which are separated from their European neighbours by formidable mountain chains, will require the completion not only of ambitious plans to lay new track and build new trains but also of projects to drill tunnels and build viaducts capable of supporting high-speed trains.
Yet it is a rare chance to see some of the longest glaciers in the Himalayas and stand at the base of a formidable mountain that you can brag is more difficult to climb – largely due to a lack of infrastructure – than Everest.
A formidable mountain, howling winds and blinding snows, lionhearted climbers who know nothing of fear.
When we attain a peak experience -- falling in love, having sex with a stranger, climbing a formidable mountain, skydiving -- we stretch our capacity to tolerate risk.
We encounter vast deserts, jungles, and formidable mountain passes in all kinds of weather: blistering heat, torrential storms, and treacherous blizzards.
Freestylers competing for world titles in a curling rink in the middle of a small-town rodeo, longboarders risking their lives on BC's formidable mountain highways, fingerboarders thriving in a remote Bavarian village, skaters from Israel and Palestine living drastically different existences mere kilometres apart, Todd fucking Falcon and many, many more.
The country retreated into almost total seclusion, forgotten behind its formidable, lonely mountains, its people reduced to a degree of ideological and political isolation for which there is hardly any modern parallel, and which endured until Hoxha's death.
