Indeed, Chicago's low lying geography, which ultimately became crucial to its boom town development (as the site of the Chicago Portage and canal), could not initially attract substantial early settlement because the tall grass prairie around its lake and river systems was underlain by hard packed glacial clay, making much of the area forbidding wetlands.[2] Thus, the paradox of Chicago's development as a city in the 19th century became taking advantage of this geography, but also overcoming its limitations.