RIO GRANDE COUNTY—On Saturday, June 17, the La Verada del Norte Chapter of the Old Spanish Trail Association sponsored a geologic road tour/field trip to English Valley, which is located a few miles northwest of Del Norte near the west fork of the Old Spanish Trail.
Before heading out to the field, a brief presentation of the regional geology and volcanic history of the San Juan Mountains, together with an overview of the geology Summer Coon Volcanic Center, was made at the Rio Grande County Museum. The tour was led by Steve Nicolais, a local, recently retired geologist and graduate from Colorado School of Mines.
English Valley is located within the remnants of the deeply eroded volcano, the Summer Coon Volcanic Center. The tour entertained and enlightened a group of 28 Valley locals and a few out of state tourists. The tour consisted of a caravan of 10 cars driving several hours throughout the basement of the 8-10 mile diameter volcanic complex. It included a number stops to observe some of the key geologic features, several huge dikes (lava filled volcanic fissures) and a variety of volcanic deposits around the flanks. The Summer Coon Complex is a first class site for the scientific study of the numerous radial dikes that emanate outward from the Intrusive center.
The Rio Grande County Museum is credited and sincerely thanked for their support and use of the room and equipment for the pre-tour presentation.