Field Notebook: Texas 1957a
Page 248
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Transcription
Decie Ranch southwest end of Lenox hills. Section 18 - 1) Conglomerate, base of unit concealed. Has a lot of Haymond type pebbles, gray sand matrix, a rather small amount of CaCO3 cement. Not knowing if the dip here is significant, I will level up through the conglomerate beds. This unit is in part covered, but the conglomerates are coarse and are the only outcropping rocks - 55', Cobbles of Conglomerate - Collection 7/20/57/10. 2) Limestone, gray calcarenite, same minor amounts of fragmental cherts, dip about 10° WNW zones within this limestone unit are quite conglomeratic. The chief distinction between this and #2 is limestone sands make up the matrix. The conglomerates peter out in about 7', but very fine pebbles are present in the limestone higher in this unit. Top of unit is very siliceous, well sorted, forms a 1" plate. Bedding below is 1' to 4'; 52'. This unit I believe equal to Lower Hess Ledge. 3) Covered 4'. PG. 121 {note: illustration: bed 1: 7/20/57/10 bed 4: 7/20/57/1 bed 9: 7/20/57/9} 4) Siltstones and very fine sandstone - siliceous cement laminar but often irregular texture; siliceous cement is secondary see 7/20/57/1, 11'. 5) Limestone, clastic, with chert pebble 1', thin to northeast thickens to southwest. 6) Like #4, 5'. 7) Like #5, 1.5', thicker to southwest. 8) Like #4, 6'. 9) Limestone, clastic, 3 beds 4" to 8" thick, each with well sorted flat tops, separated by siltstones; 3'. 7/20/57/9. PG. 122 10) Covered 3'. 11) Limestone, conglomerate, chert and quartzite large pebbles; limestone clastic sand size matrix. 1' to 2' beds; Top is same old flat surface, well sorted, and silicified 1/2" to 1". 12) Covered, 24', probably clastic limestone and conglomerate. 13) Limestone, organic frag., bryozoans, crinoid (stems) brachiopods; 7/20/57/2; 1.5'. 14) Covered, 5'. 15) Limestone, organic frag. 7/20/57/3, rubbly at base, becoming well sorted in upper 6", top 1" is silicified and laminated, top is flat. 2.5'. 16) Covered 5'. 17) Limestone, organic frag and clastic, some small chert granules - a fusuline or so, echinoid spine [2']. 18) 17' covered.