It's type section is at Canyon de Chelly National Monument in north-eastern Arizona, and the unit is also prominently, and perhaps more famously displayed in nearby Monument Valley. This deep layer is composed of many, many wedges, with steeply dipping (angles greater than 30 … 5.0 out of 5 stars 1. In 1873 one of the great geologic surveys – the Wheeler Expedition – visited Canyon De Chelly. Below is a gallery of photos of Canyon de Chelly National Monument. Its subunits, therefore, are variously called formations or members depending on the publication. 3), 1862.