The earthquake of June 27, 1925, in Montana caused considerable damage within an area of 600 square miles or more, the center of which is in latitude 46° 5' N. and longitude 111° 20' W., a short distance southeast of Lombard. It was a seismic disturbance of the first order of magnitude, but, owing to the hour at which it occurred and to other fortunate circumstances, no lives were lost and no fires broke out. The shock was startling throughout an area extending 75 miles or more in all directions from the epicenter and was sensible to persons within an area of 310,000 square miles. Within the epicentral area brick buildings suffered severely, rocks fell from cliffs, cracks opened in the ground, and the inhabitants experienced the usual symptoms of illness and emotions of alarm. Isoseismals drawn according to the Rossi-Forel scale show a wide indentation at the south due to a rapid decline of intensity in the volcanic area of Snake River Plain and Yellowstone Park.