[5][1] The early metaluminous suite (98-87 Ma) makes up the southeastern edge of the Atlanta pluton.

[4] The border zone suite (92-85 Ma) makes up the western edge of the Atlanta pluton.

[6] The Bitterroot lobe was formed in the Late Cretaceous and Paleocene, 75 to 53 million years ago.

[3][4] The Bitterroot lobe shows regional strain with foliation that strikes to the northwest and dips to the northeast, which is parallel with other natural features in the area such as the Lewis and Clark line.

[7][3] The Lewis and Clark line is an area of weakened crust where major faulting has occurred with steep or vertical dipping and striking to the northwest.