a line of demarcation between two rock strata是什么意思？

a line of demarcation between two rock strata

两个岩层间的分界线

line

n. 线条，排，行列，界线；vt. 排队，用线标出，沿…排列成行，给…安衬

例句
Every time I fluffed a line Lenny got me out of trouble with a brilliant ad-lib.
每次我台词出错时，伦尼都通过机智的临场发挥帮我解围。

of

prep. 关于，属于…的，由…制成；aux. 助动词 [非标准用语、方言] =have [主用于虚拟语气]；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

demarcation

n. 划界，立界，（工会对哪个工作由哪个工会来做的）分工，定

例句
A sharp demarcation of adventive embryos from zygotic embryos cannot be drawn.
不定胚与合子胚之间不能划分出明显的界限.

between

prep. 在…之间，私下，暗中，在…中任择其一，来往于…之间；adv. 当中，中间；

例句
How big is the abyss between what you think you are and what you actually are?
你对自己的认识和真实的你之间差别到底有多大？

two

n. 两个，两个东西，两点钟，一对；adj. 两个的，我

例句
He has been absent from his desk for two weeks...
他已经有两个星期没有坐在办公桌前了。

rock

n. 岩石，石头，摇滚乐，棒糖，<非正式>宝石（尤指钻石）；v. 摇晃，摇动，震动；vi. 演奏摇滚乐，随摇滚乐起舞；

例句
The immediate ancestor of rock 'n' roll is rhythm-and-blues.
摇滚乐直接源自节奏布鲁斯。

strata

n. 地层，岩层( stratum的名词复数 )，地层，社会阶层；

例句
The rebels came overwhelmingly from the poorest strata of rural society.
叛乱分子绝大多数来自农村的最贫困阶层。