A trough along the eastern side of what is now the Sangre do Cristo Mountains, the most southerly range of the Rocky Mountain System, was formed by pressures on the earth's crust from the west.
(A trough along the eastern side of what is now the Sangre; do; ) (A trough along the eastern side of what is now the Sangre do Cristo Mountains; was formed; by pressures on the earth's crust from the west)
A trough along the eastern side of what is now the Sangre A trough along the eastern side of what is now the Sangre do Cristo Mountains
do was formed
by pressures on the earth's crust from the west