Description Cardenas Basalt

cardenas basalt, riverside-(unspecified milepost on river). reddish dox formation @ west, basalt east.

the upper unit of cardenas basalt series of cliff-forming basaltic , andesitic lava flows interbedded beds of breccia, sandstone, , lapillite. 200 m (660 ft) thick , contains 4 six, prominent lava flows range in composition quartz tholeiite tholeiitic andesite (icelandite). of lava flows fan-jointed, ropy, , have porphyritic aphanitic , vesicular textures. sandstones within upper part of cardenas basalt contain eroded fragments of lava , have been baked overlying lava flows. lapillite bed ranges in thickness few meters several tens of meters , consists of scoriaceous lapilli, volcanic blocks, , volcanic bombs.

the basaltic , andesitic dikes , sills occur within strata underlying cardenas basalt similar in mineralogy , chemistry cardenas volcanic rocks. suggests these intrusive , extrusive rocks coeval , share common source. sills range in thickness few tens of meters thick 300 m. dikes typically thinner , locally follow fault planes.