The basin of Lake Tecopa formed between 7 and 11 million years ago , but was then tectonically stable during the Quaternary .
Tectonic or magmatic activity may be occurring north of Shoshone .
The basin of Lake Tecopa formed between 7 and 11 million years ago , but was then tectonically stable during the Quaternary , although tectonic or magmatic activity may be occurring north of Shoshone .