The phrase "a ridge at" is correct and usable in written English.
It can be used to describe a specific location or feature related to a ridge in geographical or topographical contexts.
Example: "The hikers reached a ridge at the summit, offering breathtaking views of the valley below."
Alternatives: "a ridge located at" or "a ridge situated at".
"I remember standing on a ridge at Blue Sky three years ago as it was evolving.
After leaping off Taft Point late on Saturday, Potter and his wingsuit partner, Graham Hunt, crashed into a ridge at California's Yosemite National Park.
They got off the lift, scooched along a snowcat-track, then peered down the nose of a ridge at the bounty spread below their ski tips.
"Why?" We were resting below a ridge at the highest snow-covered point on the mountain, and the path he had chosen for us was rocky and precipitous.
The pectoralis major extends across the upper part of the chest and is attached to a ridge at the rear of the humerus (the bone of the upper arm).
Bago Mountains, Burmese Bago Yoma, also called Pegu Mountains, mountain range of south-central Myanmar (Burma), extending 270 miles (435 km) north-south between the Irrawaddy and Sittang rivers and ending in a ridge at Yangon (Rangoon).
Meanwhile Hunt and Da Namgyal Sherpa left loads for a ridge camp at 27,350 feet (8,335 metres).
We camped in a ridge tent at the edge of town one summer (naturally managing to avoid the theatre – didn't have the money or temperament for that).
Sutton, hugging the contours of a mountain in the Swiss canton of Valais, hit a ridge travelling at about 125mph and died instantly.
He stood on a ridge looking at the Palestinian town of Tzurif across the valley, an M-16 across his shoulder.
The red dotted arrows show a shallow, disrupted landslide originated from a ridge (located at 28.08°N, 85.208°W).
