Several of the later eruptions involved not only basalts, but lavas made of rhyolite or dacite. Such lavas contain greater amounts of silica, and are more viscous than basalt. These eruptions created most of the highest peaks in the Jemez Mountains, including Chicoma Mountain (11,561 feet), and Polvadera Peak and Pajarito Mountain. Weathering of the igneous rocks resulted in alluvial fans, which spread eastward into the Rio Grande Rift. By 2 million years ago, the sediments had displaced the Rio Grande eastward from an earlier location near Los Alamos to its current location in White Rock Canyon. Two more eruptive cycles took place approximately 1.6 and 1.25 million years ago. The first eruption created the Toledo Caldera, but this feature was largely obliterated by the later Valles eruption. Each eruption involved pyroclastic flows and produced some of the welded tuff now found west of the Rio Grande. There have been numerous eruptions of sticky lavas in the last 1.25 million years ago, but all have been within the Valles Caldera. The most recent eruptions took place about 40-50,000 years ago, and formed the El Cajete Crater. This crater lies at the foot of Redondo Peak, a resurgent dome that rises to 11,254 feet within the Valles Caldera. Lying between White Rock Canyon and the rim of the Valles Caldera is the Pajarito Plateau, the many canyons of which have been cut by relatively recent erosion.