The Toronto ravine system is a distinctive feature of the city's geography, consisting of a network of deep ravines which forms a large urban forest that runs through most of Toronto. The Ravine and Natural Feature Protection Bylaw protects approximately 11,000 hectares (27,000 acres) of public and privately-owned land; and is the largest ravine system in any city in the world. The ravine system has been presented as a central characteristic of the city, with the size of the ravine system leading Toronto to be described as "a city within a park". The ravine system began to take shape approximately 12,000 years ago; when the glaciers that once covered Toronto retreated northeast, leaving rivers and valleys in its place. Due to the topography of the ravine system, limited urban development occurred within it until the mid-19th century. During the late-19th and early 20th centuries, the ravine system underwent a number of changes and saw several infrastructure developments built within it. Limited development in the ravine system continued until Hurricane Hazel passed through Toronto in 1954; when the destruction caused by the hurricane resulted in the cessation of almost all major developments in the ravine system. The Toronto ravine system remains largely undeveloped, with most of its public lands having been designated as parkland. Although large portions of the ravine system remain undeveloped, it continues to be used by the city for flood management, carbon sequestration, and recreational activities. In addition to its human uses, the ravine system also serves as a habitat and wildlife corridor for a large number of animals.
The Toronto ravine system is a distinctive feature of the city's geography, consisting of a network of deep ravines which forms a large urban forest that runs through most of Toronto. The Ravine and Natural Feature Protection Bylaw protects approximately 11,000 hectares (27,000 acres) of public and privately-owned land; and is the largest ravine system in any city in the world. The ravine system has been presented as a central characteristic of the city, with the size of the ravine system leading Toronto to be described as "a city within a park".

Andries Gerrit Knevel (born 13 February 1952, Naarden) is a Dutch theologist, author and presenter on Dutch radio and tv. He is the former program director of the Evangelische Omroep, a Dutch broadcasting organisation with Protestant foundations.