Qual o significado de "slow-sloping"?

Olá, gostaria de saber o significado de "slow-sloping" no seguinte trecho:

"I found myself staring out the window. I was looking at the wooded, slow-sloping hill beyond the lake. And from Hyde's classroom, things did seem connected: The trees seemed to close to the hill, and just as I would never think to notice a particular cotton thread in the magnificently tight orange tank top Alaska wore that day, I couldn't see the trees for the forest (...)"

Trata-se de um recorte do livro Looking for Alaska, do John Green, de 2005.