Thick diamondiferous gravel terrace deposits along the lower Orange River, southern Namibia, provide a rare opportunity to investigate controls on the incision history of a continental-scale bedrock river.
The relief of Finland was greatly affected by Ice Age glaciation.The retreating continental glacier left the bedrock littered with morainic deposits in formations of eskers, remarkable winding ridges of stratified gravel and sand, running northwest to southeast.
It shows how little we still know about the bedrock below large continental ice sheets".
RSD substrate accounted for 3.6% of the California continental shelf, compared to 8.4% for bedrock reef substrate.
Rather, these contrasts reflect the interplay between bedrock lithology of the continental shelf, rates of sediment delivery, sediment texture, meltwater volume and relative size of ice-sheet drainage basins.
The first "minimum" model envisages a restricted ice sheet, with exposed nunataks in coastal areas and limited ice extent onto the continental shelf fed by ice flowing through bedrock troughs.
Fluvial material, likely derived from the main drainage divide zone, preferentially accumulates in the middle continental shelf, whereas material representing erosion of older bedrock (Torlesse Terrane), located lower in the drainage basin, is dispersed uniformly across the shelf.
Spatial analysis was then used to quantify the distribution and abundance of RSDs and determine the percentage of bedrock reef, sedimentary and RSD substrates on the continental shelf within state waters.
The great continental and oceanic plates of crust are always moving, rubbing, rearranging the bedrock of our lives.
