I'm learning geology to understand the processes behind the formation of my local landscape.
I understand the processes behind big features, such as mountains. But I'm struggling to understand the processes behind small local features, such as hills.
I live in Reading, Berkshire, South-East England, with a typical landscape of rolling of grassy hills and clay strata. Similar to this image below.
What geological processes would be responsible for the formation of this landscape?
Additional Information
Strata:
I dug a hole in my garden and found there is a thin layer of soil, then a large amount of clay with a variety of rocks and pebbles.
Features:
The main features are a landscape of rolling-hills and grassy plains.
Question
What geologic processes are responsible for the formation of these low-hills and clay strata?
Were the hills once mountains, now eroded?